PHYSIOLOGICAL CHEMISTRY.THE year 1911, so far as Physiological Chemistry is concerned, hasbeen one of quiet, uninterrupted progress, but i t cannot be describedas an eventful year. There is no great discovery to be chronicled,and no research or series of researches stands out conspicuouslyamong its fellows.Amongst those who have passed away, one must specially mentionthe names of Dr. Pavy and Professor Christian Bohr.Dr. Pavy was one of those few indefatigable spirits who, likeDr. Ringer, whose lo~sss we had to deplore last year, was able tocarry out important scientific work in the midst of a life of busymedical practice. He is best known as the redoubtable opponent ofClaude Bernard’s views on carbohydrate metabolism, and he con-tinued almost up to the day of his death, at the ripe age of eighty-four, to work a t the subject he had made his own.I n the last fewyears he became interested in the part played by the colourlesscorpuscles of the blood in the transport of substances absorbed fromthe intestine, and his la& paper,l published posthumously, dealswith the power these corpuscles have in incorporating dextrose intheir protoplasm. Pavy’s familiar figure will be much missed inmedical and physiological cir,cles, and the world will be the poorerby his absence.One iittle thought last year when penning the section of the reportdealing with the subject of respiration, that it would be necessarytwelve months later to deplore the loss of Christian Bohr, of Copen-hagen, the leader and inspirer of those researches which haveculminated in our present knowledge of the processes involved inbreathing.Although all of Bohr’s deductions from his experimentshave not been universally accepted, especially in relation to the partplayed by the so-called ‘’ vital factor,” i t cannot be denied that itwas the boldness and novelty of his conceptions that led others totake up the subject afresh, and test them by further experiment.Unlike Pavy, Bohr was a comparatively young man, and his beingF. W. Pavy and W. Godden, “Carbohydrate Metabolism and Glycosuria,”J. Physiol., 1911, 48, 199 ; A,, ii, 1001.18PHYSIOLOGICAL CHEMISTRY. 183suddenly cut off in his prime adds exceptional sadness to the regretat his death which is so universally felt.The year has been singularly destitute of chemical or physiologicalCongresses.The British Association and the British Medical Asso-ciation have had their usual annual meetings with their physielogical sections. I n the case of the latter body, physiology wascombined with anatomy in one section, and the major part of thepapers read were anatomical. The Portsmouth meeting of theBritish Association for the Advancement of Science was a cornpar*tively small one, but was not less interesting on that account. It, infact, often happens that interest and fullness of attendance are ininverse proportion. This was certainly the case with the sectionof Physiology, whilch was opened by a highly speculative addressby the President;, Professor Macdonald, and was followed by anumber of well-sustained discussions on important subjects, Thesection of Chemistry also was notable for the address of its President,Professor James Walker, on the history of Physical Chemistry,which is now so intimately associated with the latter-day developments of physiology.The foundation of the Bio-chemical Club in London during theyear is an indication that biechemists are realising, not only theirstrength, but also the importance of union, which forms so large anelement in strength.Its meetings hitherto have been highlysuccessful, and are combinations of scientific discussion with themore social intercourse which accompanies and follows the eatingof dinners. The Club is looking forward with hopefulness to a not-distant future when it will develop into a Society with a journalof its own.Among the new books of the year it is necessary to mention atext-book of comparative physiology by Professor Putter.2 Thisis not of the same ambitious character as that edited by Winter-stein, t o which allusion was made in last year’s Report, but it isnevertheless a comprehensive treatise, and not too bulky.I n theinvestigation of the lower, as well as of the higher, animals, chem-istry is playing a conspicuous part, and in Professor Putter’s bookspecial prominence is assigned to the r61e of physical chemistry inthe elucidation of vital problems.Another book which may be read with interest and profit isentitled, “ Chemical Phenomena in Life,” and its author is ProfessorFrederick Czapek,3 of Prague.It only extends over 148 smallpages, but the amount of information packed within this smallcompass is really remarkable. There is no indication of undue2 (‘ Vergleichende Physiologie.” A. Piitter. FiJcher ; Jena, 1911.3 Harper’s ‘‘ Library of Living Thought,” 1911184 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.compreseion; the facts are stated in a clear, convincing, and com-prehensible style. Professor Czapek is a botanist, but he dealswith his subject from the point of view of general biology. Heshows how many of the phenomena of life are rendered intelligiblein the light of colloid chemistry, and by the conception of enzymesas organic catalysts. The same subject may, of course, be studiedin larger and more elaborate treatises, but to those who are notphysical chemists, a little book of this nature is a veritable godsend;it gives in outline the main facts, the new ideas, and explainsl insimple terms the new language which has been introduced intoscience by the physical chemists.Periodical literature, as I have already indicated in my openingsentence, remains quite as voluminous as in former years.To siftthe chaff from the wheat is not possible a t present. That only canbe performed by the reviewer of the future. Many pieces oforiginal work which appear valueless a t the time of publicationoften turn out to be of exceptional importance, and the converseis equally true. It is also impossible to attempt, even in outline,a survey of the whole output of the year or to classify it.Thepublished papers deal with practically every branch of the subject.The only remaining alternative is to follow my custom of previousyears, and make a selection, which I trust will be found a judiciousone.I propose, then, in the first place, to deal with one or twopoints of nomenclature ; next, rapidly t o review a certainnumber of papers which appear in my judgment to beof exceptional interest, and, finally, to select for rather moreextended notice a few of the topics which are attracting attentiona t the present day. In this preliminary stage of my essay it isimpossible to forecast with certainty what these topics will be, buta t this point my intention is to deal with three only: first, theenzymes concerned in nuclein metabolism, a somewhat specialisedand technical albeit important subject; secondly, the vexed ques-tions which have centred around “Standard Bread,” a subject ofinterest even to the man in the street; and the third subject willbe a pathological one, namely, the causation of that tropical diseasewhich is named “beri-beri.”Some Questions of iVomenclatu>re.The terminology of enzymes has settled down in the majority ofcases to the following rule.They are usually named after the sub-stances they split up, and end in the affix ase ; for instance, maltase isthe name for the enzyme which decompmes maltose into the smallePHYSIOLOGICAL CHEMISTRY. 185molecules of dextrose, lipase for a fat-splitting enzyme, and so forth.In many cases the reaction is a reversible one, and the same agentwhich produces the decomposition under certain conditions, willunder certain other conditions produce a synthesis of the simplerinto the more complex material.The main condition which influ-ences the result is, w is well known, the law of the influence ofmass action. Hans Euler and S. Kullberg have, however, pointedout that in certain cases, a t any rate, one enzyme is employed inthe cleavage, and another enzyme comes into play in the syntheticact. They could find no evidence that the enzyme which builds upphosphoric acid esters of carbohydrates, and which is found inyeast and other moulds, has any action a t all in splitting up theseesters into their component parts.Euler5 suggests that in suchcases the termination ese should be adopted instead of ase, andconsequently speaks of the enzyme in the example just quoted asp7hosphates_ee. Another instance where such a system of terminologywould be useful is what E. S. London entitles, ‘‘ A reversible phenemenon in the action of intestinal juice on the products of caseindigestion”; at a certain stage the milk protein undergoes jellying,and the subsequent liquefaction is apparently the result of theaction of a different enzyme.Life, so far as its chemical activitim are concerned, has recentlybeen defined as consisting of a series of reversible reactions. Thisis probably as correct a definition of vital metabolism it5 is possiblein the present state of knowledge, but like all terse attempts tocompress within a very small nutshell a very complex problem, itlacks completeness, and allows of no exceptions, which are doubtlessplentiful.Be that as it may, reversibility is observable in living structuresin cases which permit of no obvious chemical explanation. In therealm of psychology, bhe only region in wliich, according toCzapek in the book already mentioned, physicechemical laws arenot a t present applicable, a- change of mind and a recantation ofviews are not entirely unknown.Coming, however, to more matterof fact phenomena, Sherrington has furnished many instances wherereversal of normal nerve action may be brought about under theinfluence of certain drugs, for example, chloroform. These ar0 notlimited to blood-pressure effects which he had studied in his earlierwork, but may occur also in reflexes carried out by skeletal muscles.7Another example is furnished by the investigation carried out byZcilsch.physiol. Chem., 1911, 74, 15; A., i, 1051.Ibid., 13 ; A, i, 1051. Ibid., 301 ; A . , ii, 1000.7 C. S. Sherrington and Miss S. C. M. Sowton, J. Physiol., 1911,42, 383 ; d., ii,753 ; see also Owen and Sherrington, Strychnine Reversal,” ibid., 43, 232186 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Dale and Laidlaw 8; they found that cytisine, the alkaloid oflaburnum seeds, has an action similar to that of nicotine in lessen-ing or reversing the usual effect of stimulation of the chorda tympaninerve in producing an increased flow of saliva.Another a.phorism a good deal older than the one quoted a fewparagraphs back, is that language was given to man in order toconceal $is thoughts. One cannot help thinking of this whendealing with the second case I take under the heading nomencla-ture; I mean the introduction of the appalling word aprrhegma;thus among this year’s Abstracts I find the title, “P-Alanine as aBacterial Aporrhegma.”g The word was first introduced a yearor two ago, but would be better expunged from the literature.The meaning of the word is a substance split off by biologicalaction.Another new and useful word is acupniu, which has been intro-duced by Dr.Yandell Henderson, and is gaining acceptance.Carbon dioxide has in the past been looked upon chiefly as a wasteproduct, and of but little use to the organism.We now know thatcarbon dioxide fulfils inter alia the useful office of being the normalstimulus to the respiratory centre, and it assists in the dissociation ofoxy-haemoglobin in the capillaries. I f , owing to forced and exagger-ated respiratory efforts, this gas is swept out of the blood so thatits quantity is reduced below a certain “ threshold,” the respiratorycentre is no longer thrown into action, and cessation of breathing(apncea) is the result. I n normal circumstances, when thecarbon dioxide again accumulates, respiration sets in once more.There are, however, certain conditions in which it lessening of thecarbon dioxide content in the blood may produce a cessation ofbreathing, which is serious or even fatal.Notable among theseconditions is that produced by surgical and other forms of shock.”Henderson has worked out this aspect of the question in a seriesof researches, and has bestowed the term “ acapnia ” to the diminu-tion of the carbon dioxide, which is the cause of the symptoms.The latest of this series10 appeared about the middle of the year,and in this it is pointed out that acapnia is a frequent concomitantof the glycosuric state, and that in certain forms of experimentaldiabetes, prevention of acapnia obviates disturbances of the sugar-regulating functions. As long ago as 1889, Labousse pointed outthat injection of “ peptone ’’ causes acapnia, although he did notemploy that expression; it is now found that this also leads to8 J.Physiol., 1911, 43, 196 ; A., ii, 997.9 D. Ackermann, Zeitsch. Biol., 1911, 56, 87 ; A., ii, 757.10 ‘(Acapnia and Glycosuria,” Y. Henderson and F. P. Underhill, Amer. J.Physiol., 1911, 28, 275 ; A., ii, 813PHYSIOLOGICAL CHEMIBTRY. 187hyperglycaemia. It is often a long time before physiological dis-coveries filter through to the rank and file of medical practitioners,but one is rejoiced to hear that practical physicians are alreadyappreciating the va.lue of Henderson's work, and are thus beginningt o realise, not only the importance of carbon dioxide in the body,but also the meaning of symptoms which previously puzzled them.A mention of diabetes prompt,s one a t this point to allude byway of parenthesis to an important paper by F.P. Underhill andM. S. Fine11 on pancreatic diabetes. The hypothesis they advancecan only be fully understood by studying the paper in full, a taskthat will amply repay the reader. The underlying assumptionis that there exists between the liver, pancreas, and adrenal bodiesan inter-relation which keeps the amount of blood sugar constant.The action of the internal secretion of the pancreas is to facilitatecarbohydrate katabolism ; therefore, when the pancreas is removedor its function is in abeyance, sugar aocumulates, because theopposing effect of the adrenals has full sway. On the other hand,if adrenal function is in abeyance, the deleterious effects of depan-creatisation are lessened ; they find that hydrazine prevents theglycosuria which occurs after extirpation of the pancreas, in allprobability because this drug diminishes adrenal activity.Pnein and antipmein are illustrations of names of unknownsubstances whiEh are derived from their physiological action.Pnein or pneumin is a thermostable material found, according toBat'telli and Stern,12 in most tissues which accelerate t.heir primaryrespiration processes.Antipnein or antipneumin is destroyed bya temperature of 6 5 O ; it is specially abundant in the spleen, andalmost absent in muscle. Its na.me indicates that it inhibits orhinders oxidative processes. Whether such terms " catch on " andlive depends on many circumstances. Many words become familiar-ised by long usage before their chemical composition is worked out,and so the old names stand. There is little doubt, for instance, thatadrenaline and secretin are destined for a long life.Peptone andprotagon are still used, although they can no longer be regardedas connoting chemical individuals. The prolonged existence ofPopielski's vmo-dilatin appears more questionable, and the con-tinued use of the word " ptomaine '' also appears undesirable. Thehistory of our knowledge of the bases obtainable from proteins is avery interesting 0118.13 Many of them can be obtained by simplyremoving carbon dioxide from amino-acids, and one of the latestof these obtained in this way from histidine is 4-p-aminoethylgly-l1 J. Biol. Chern., 1911, 10, 271 ; A . , ii, 1001.l2 Biochem. Zeitsch., 1911, 33, 315 ; 36, 114 ; A., ii, 748, 1008.l 3 See article by G.Barger, Science Progress, 1911, p. 221188 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.oxaline or ~-iminazolylethylamine.~4 This is a constituent of ergot,of the intestinal mucous membrane, and is probably identical withPopielski’s vaso-dilatin. Its effects are also similar to thoee whichare produced by a toxic substance formed in an anaphylactic animalby the injection of an innocuous protein.However desirable it may be for sentimental or historical reasonsto retain words which have become familiar, there can be no doubtwhatever that words framed on chemical misconceptions ought to beruthlessly expunged. Such a word, for instance, is “ quadriurate.”Rosenheim 15 was the first to prove that these substances, originallydescribed by the late Sir William Roberts, are mixtures of biuratesand uric acid.This view has been repeated and confirmed byR. Kohler16 during the present year, who was unacquainted withRosenheim’s work. W. E. Ringer17 has also investigated the samequestion, and although he lends no support to the chemical entityof these substances, suggests that the peculiar behaviour of uraticdeposits in urine, which originally led Sir W. Roberts to his viewthat uric acid and a biurate were united chemically, can be bestexplained on the view that this is a case of “ solid solution.”Another case of nomenclature, and the last on my list, is thatof caseinogen and casein. It was in the year 1890 18 that I proposedthese names for the principal proteins in milk and cheese respec-tively, as previous to that time the single word casein was usuallyapplied to both indiscriminately, and this led to confusion.Thewords certainly possess the merit of conveying to the mind easilythe relationship of the two substances to one another, and this isby no means unimportant, especially to those who have to deal withstudents. The terms were obviously suggested by the somewhatsimilar genetic relationship between fibrinogen and fibrin, and theanalogy still holds, although it may not be complete in every detail.They have been very generally adopted by those who write in theEnglish tongue, but those who write in German continue t o employthe word ‘‘ casein ” for the milk protein, and the word ‘‘ paracasein ”for the curdled prsduct.19 I n view of this international difficulty,14 Barger and Dale, J.Physiol., 1911, 41, 499 ; Dale and Laidlaw, ibid., 43, 182 ;d., i;, 217, 1017. See also, in this connexion, W. H. Harvey, J. Path. Bact.,1911, 16, 95 ; A., ii, 1013, on the part played by such bases in the production ofkidney disease ; and in the causation of high blood pressure, see Bain, Zancet, 1911,i, 1409 ; A., ii, 631.l5 Rosenheim and Tunnicliffe, Auncet, June 16th, 1900.16 Zeitsch. physiol. Chem., 1911, 70, 360 ; A., i, 243.l 7 B i d . , 75, 13, A., i, 1044.19 Recent intercsting {work on milk curdling, especially on the changes in theprotein antecedent to actual curdling, and amplifying Hammarsten’s classical workSee also Rosenheim, ibid.,71, 272 ; A., i, 403.l8 J.Physiol., 1900, 11, 448PHYSIOLOGICAL CHEMISTRY. 189I recently put the question to our newly-founded Bio-chemicalClub whether it would be wise to surrender the use of the wordscaseinogen and casein in favour of the German system, and I wasglad to find almost complete unanimity in favour of my own terms.They will therefore continue to live on, and if the Germans do notfall into line, no one need suffer, except perhaps the Germanstudents, who will continue to wonder why the protein of milkshould be called cheese, and why the protein of cheese is calledsomething else.Miscellaneous Papers of Interest .I now come t o the second item on my programme, namely, briefnotices of various papers whiich appear to me important ones.Finding it difficuh to arrange them in any logical order, I proposeto take them almost haphazard, and will first allude to some on thesubject to which I was referring in my last paragraph.Milk.-The vexed question whether pepsin and rennet aredifferent enzymes or not still continues to excite interest.The prosand cons are about equally balanced if one, counts numbers; butwhen one looks to the authoritative quality of the writers, thebalance of evidence this year, a t any rate, appears to be in favourof the old view that the two enzymes are distinct. The most con-vincing of these papers is that which has been written by theveteran ‘Olof Hammars*n,20 who from the first has dkputedPawloff’s view that the two enzymes are identical. One is glad tosee that Rammarsten, who has resigned his professorship, is stillactive in research.He has continued, for example, his work onthe bile of the rarer animals, and this year has investigated that ofthe hippopotamus,21 and found that further varieties of bile acidsexist in the animal kingdom than those which were previouslyknown. He has also since his retirement produced a new editionof his well known text-book,22 and that has been followed by anEnglish translation by Professor Mande1.23To some extent the milky mantle has fallen apon ProfessorHammarsten’s successor a t Upsala, Professor Hedin, who contri-butes a paper on the “Specific Inhibition of Rennet and Differencesbetween Rennets.”a He finds that by warming neutral infusionson the subject will be found in a paper by Bang (Sknnd.Arehiv. Physiol., 1911,25, 105 ; A . , i, 826).2o Zeitsch. physiol. Chem., 1911, 74, 142 ; A., ii, 998.21 Ibid., 123 ; A., ii, 1010.z2 “ Lehrbuch d. physiol. Chem.,” 7th edition, Wiesbaden, 1910.23 (‘ Textbook of Physiol. Chem.,” translation of the above, Wiley, New York,1911.2J Zeitsch. physiol. Chem., 1911, 74, 242 ; A., ii, 998190 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of the gastric mucous membrane of the guinea pig, calf, and pikewith dilute ammonia and then neutralising, substances are formedwhich inhibit rennetic action, but the inhibitory substances onlyinhibit the rennet of the animals used. The conclusion is drawnthat this specific action indicates that the enzymes they inhibit, arespecific also.This conclusion would have been strengthened if ithad also been shown that the rennet, say, of the calf did not producecurdling of the milk of other animals. There is no word aboutthis; in fact, all the evidence points the other way; so far as isknown, the rennet from any animal will curdle any species of milk.Heat Coagulation of Proteins.-This question has been taken upby Dr. C. J. Martin and Miss Chi~k.~5 They show in the new lightshed by physical chemistry on colloids, and in the new language ofthat science, that many of the old facts become intelligible. Heatcoagulation is not a mere temperature effect, but is really a reactionbekween protein and water, and is influenced by temperature inaccordance with the law of Arrhenius, the temperaiure-coefficient,however, being a very high one.This “ denaturation ” of the proteinis followed by the separation of the altered protein in particulateform (agglutination). The first step, denaturation, is, if meansare taken t o prevent changes in acidity, a reaction of the firstorder; as the protein is precipitated, free acid is progressivelyremoved from the solution, and this second change, “ agglutination,”occurs more rapidly than the, denaturation. A number of otherissues are disfcussed, such as the influence of salts on the pheno-menon, but these the reader must discover for himself. My objectis fulfilled by calling attention to this interesting research.The Use of Elastin for Isolating Pepsin.-The annual output byAbderhalden and his colleagues continues unabated.Most of itis useful spade work, working out details on the lines of previousresearches: the digger may chance to unearth a precious stone nowand then. Abderhalden’s 26 precious stone this year is the discoveryof the usefulness of elastin for the isolation and detection of pepsin.It has long been known that if fibrin is placed in a solution con-taining pepsin, the enzyme is adsorbed and removed, and can besubsequently washed out from the fibrin. Elastin and other solidproteins act in a similar way, but the special advantage of elastinis its comparative insolubiiity in digestive juices, so that subse-quently the enzyme can be obtained almost free from proteolyticproducts.Other enzymes are adsorbed in a similar way, but so farAbderhalden has confined his work almost exclusively to pepsin.25 J. Physiol., 1910, 40, 404; A., 1910, i, 597; ibid., 1911, 43, 1 ; A., i, 822.26 Zeitsch. physiol. Chem., 1911, 71, 315, 339, 449 ; 74, 67, 411 ; A . , i, 511 ; ii,506, 999PHYSIOLOGICAL CHEMl STRY. 191By this method i t has been shown that proteolytic enzymes areabsent from the fzeces, but by far the most important resultobtained is the presence of pepsin in an active form in the intestine,into which it is carried and protected by the elastin or other com-paratively insoluble proteins of the food. Hitherto, it has generallybeen supposed that the action of pepsin ceases beyond the confinesof the stomach.There is still a large amount of ignorance inrelation to the individual pax& played by pepsin, trypsin, anderepsin in protein cleavage, but it can hardly be doubted that inclearing away this ignorance investigators will have in the futureto consider a new factor, namely, the co-operation of the gastricenzyme pepsin with the others in the much more complete digestiveprocess which takes place in the small intestine.Origin of the Hydrochloric Acid of the Gastric Juice.-Passingnext to the inorganic ally of pepsin, we come across an interestingpa.per by Miss Fitzgerald.27 Many workers have employed variousmicrochemical tests in order to localise the seat of formation ofthe acid of the gastric juice, and although the evidence availableclearly points to the association of acid formation with the parietalor oxyntic cells of the gastric tubules, no absolute certainty hasbeen attained; neither has i t been proved beyond cavil that hydro-chloric acid exists in demonstrable form in the secretion before itreaches the free surface of the mucous membrane.This has nowbeen finally set at rest. Solutions containing potassium ferrocyanideand ammonium ferric citrate were injected into rabbits and guineapigs, and the animals were killed from three to thirty hours later.This mixture readily formed Prussian blue with hydrochloric acidof a much less concentration than that contained in gastric juice,but gave no reaction with sodium phosphate or carbon dioxide.Microscopic sections of the stomach showed the presence of Prussian-blue in the lumina of the gland tubules and in the canalicdi of theparietal cells.The acid is thus shown to be already in a free statein the secretion of the cells which form it. A faint blue colorationthroughout the protoplasm of the same cells seemed to indicateits presence there too. The chemical operations involved in theliberation of the free acid from chlorides is another questionaltogether; but excess of chlorides in the parietal cells as comparedwith the asmount in the pepsin-forming cells was shown to bepresent.The Physiological Protein Minimum.--I do not mean here toreopen the old question which the name Chittenden suggests, butto look a t the subject from another point of view. During stam&tion the loss of nitrogen per day soon reaches a constant level,27 Proc.Roy. Xoc., 1910, B, 83, 5 6 ; A., ii, 50192 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.and in this condition it might be thought that if protein wereadministered in such amount that its nitrogen equalled the lw, thedrainage of nitrogen from the body would be arrested. Theclassical experiments of Voit showed, however, that nitrogen equili-brium is not reached until the amount given is two or three timesgreater than the amount lost during inanition. In 1909 LouisMichaud 28 attacked this problem afresh, using dogs, as Voit did inhis experiments, with the conclusion that the result varies accordingto the sort of protein used in feeding. A mere nitrogen estimationin the food protein is not enough; the value of a protein dependsrather on the proportion between its cleavage products.If aprotein foreign to the body, such as edestin, is used, equilibriumwas not reached until excess was given as stated by Voit. But ifthe food protein employed was the flesh or other tissues of anotherdog, then equilibrium is reached more easily; in fact, it can beattained by giving just enough to replace the inmition daily waste.Horse flesh or casein were intermediate between edestin and dog’sflesh in this relationship.This paper attracted much attention, and, put in a sentence, themain conclusion is that a live dog can make its tissues most easilyfrom dead dog. I f this were pushed to a logical conclusion, wemight even formulate a scientific defence of cannibalism.Howeverlikely such a conlclusion might appear to the superficial thinker,it would really upset much of the recent knowledge acquired bypainstaking work on protein metabolism. We know with almostabsolute certainty that a small fraction only of the protein ingestedis actually used as a “flesh-forming food”; the larger fraction isalmost immediately cast out as waste in the form of urea. It is,however, quite conceivable that thisl waste might be lessened byusing protein food as near as possible in composition to the proteintissues peculiar to the species of animal under observation.A good many people have taken up the point. Frank and Schitten-helm29 confirm the general idea; they find that the minimumamount of protein capable of maintaining nitrogenous equilibriumafter inanition is appreciably less when the protein administeredis the protein of dog’s muscle than it is when any other kind ofprotein is employed for feeding purposes.Other workers,3O however,find that the advantage of feeding dog on dog, although present, isnot a very great one. This is what one would rather have antici-pated. Even Frank and Schittenhelm31 found in their further28 Zeitsch. physiol. Chem., 1909, 59, 405 ; A., 1909, ii, 498.2g Ibid., 1910, 70, 98 ; A . , ii, 127.30 See, for instance, von Hoesslin and Lesser, ibid., 1911, 73, 345 ; A., ii, 904.31 Ibid., 157 ; A., ii, 904.Also London and Rabinowitsch, ibid., 1911, 74, 312 ; A . , ii, 999PHYSIOLOGICAL CHEMISTRY.193work that in ordinary nutrition (apart from inanition) nitrogenousmetabolism runs practically the same course, whatever form ofprotein was given in the food.Synthesis of Amino-acds in the Uocly.-A series of papersinitiated by Franz Knoop on this subject bids fair to yield impor-tant results. He showed 32 that a-amino-acids after parting withtheir amino- and carboxxl groups are broken down in a mannersimilar to the next lower fatty acid, and that they may be acetylatedin the bodies of animals. Further, a-ketonic acids may take upnitrogen in the body with the production of optically active a-amino-acids ; a-hydroxy-acids may also be converted into a-amino-acids.Embden and Schmitz,33 by means of perfusion experiments on theliver, discovered that p-hydroxyphenylpyruvic acid was convertedinto tyrosine by that organ, and that after perfusion with p-phenyl-pyruvic acid, phenylalanine could be isolated in the form of a carb-amic acid; leucic acid gave rise to leucine-carbamic acid.I f the liverwas rich in glycogen, during simple perfusion part of the glycogenga-ve rise to alanine, lactic acid and pyruvic acid being apparentlyintermediate products. Knoop and Kertess 34 fed a dog on a-amin+y-phenylbutyric acid, and its urine contained the I-modification ofthis acid, its acetyl derivative, and d-a-hydroxy-y-phenylbutyric acid.In addition, butyric acid was formed, indicating degradation ofthe amineacid through the ketonic acid to the next lower fattyacid. When fed with the a-ketonic acid, the products wered-a-hydroxy-7-phenyibutyric, acetylaminophenylbutyric, and hip-puric acids.The formation of the same hydroxy-acid in bothinstances, and in larger quantity from the ketonic acid, is confirma-tory of the view that the amino- is converted into the ketonic acidin the animal body. The acetylamino-acid is also in each instancederived from a probably inactive intermediate compound, and notby direct acetylation, as Neubauer and Warburg 36 considered t ooccur in perfusion experiments on the dog’s liver.The Corpus Luteurn.-The year’s work contains a good deal aboutinternal secretions in general, and adrenaline in particular, but Ipass from these to consider one point only. It is well known thatafter the exit of the ovum from the ovary, its follicle is filled upby the growth of yellow-coloured cells, and that the corpus luteumso formed attains a great size if pregnancy ensues.It has beengenerally assumed that these cells form a hormone,” and thefunction generally attributed to this chemical messenger is to sssist32 Zuitsch. yhysiol. Chem., 1910, 67, 489 ; A . , 1910, ii, 880.yJ Bioc;h(vn. Zeitsch., 1910, 29, 423; A . , ii, 53.‘I4 %Cit.wh. physiol. Chem., 1911, 71, 252 ; A, ii, 514.35 Ibid., 1910, 70, 1 ; A . , ii, 53.KIt‘P. -VOL. VIII. 194 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.in some way in the successful fixation of the ovum in the uterus.Another series of observations on the causation of growth in themammary glands, culminating in milk production, failed to revealthe presence of any secretory nerves in the milk glands, correspond-ing with what are known to exist in the salivary and sweat glands;and evidence that mammary growth occurs in cases where therecan be no possible nervous connexion between the generativeorgans and the mammary glands pointed to the conclusion thatthe correlation must here be chemical rather than nervous.A fewyears ago Professor E. H. Starling, working with Miss Lane-Claypon, thought that the hormone in question must be secretedby the foetus, because injection of faetal extracts led to a somewhatimperfect hypertrophy of mammary tissue. Doubt was, however,felt in many quarters whether this could be the whole explanation,for mammary evolution occurs in many virgin animals, in whichovulation is not followed by pregnancy.C. H. O’Donoghue36 hasinvestigated the question recently in the Marsupial cat known asDasyurus, which from many points of view, into which it is unneces-sary to enter here, is a particularly suitable animal for the solutionof the problem. He finds a close correspondence between the stagesin the development of the corpus luteum and the mammaxyglands, and finally concludes that it is the hormone secreted bythe former which is the inciting cause of the growth of the latter.On the other hand, F. $1. A. Marshall,37 who has investigated asimilar question in the dog, arrives at the conclusion that theinternal secretion from the ovary, which brings about I‘ heat,”originates in the interstitial cells of that organ.It is quite possiblethat the ovary may form more than one internal secretion, andonly one of these acts on the mammary glands.The Effect of Choline o n Blood Pressure.-Mott and I appear tohave been the first to recognise the physiological and pathologicalimportance of choline. It is a base derived from the cleavage ofcertain phosphatides, notably lecithin. Its presence in such fluidsas that which bathes the spinal cord and brain would be a tangibleproof of the disintegration of nervous matter such as occurs inmany of the grosser diseases of these organs, for phosphatides hereare much more abundant than in other tissues. Many physiologistshave taken up the choline question, and some have entirely deniedthe existence of choline in the cerebrespinal fluid, even after36 Proc.yhysiol. Soc., 1911, xvi. ; J. Physiol., 43 ; Quart. J. Micro. Scknce,1911, 57, 187. Another paper on the corpus luteurn calls attention to certain toxicefl’ects produced by a lipoid substance that can be extracted from i t (Bonin andAiicel, Compt. rend., 1910, 151, 1391 ; A . , ii, 129).j7 Proc. pl~ysiol. SOC., 1911, xxi ; J. Physiol., 43PHYSIOLOGICAL CHEMISTRY. 195massive disintegration. It may be freely admitted that the testahitherto devised for identifying the base are only relatively con-clusive, for sufficient material has never been collected for acomplete anaiysis. All, however, seem now to admit that thematerial which is undoubtedly present and so distinguishes thepathological from the normal fluid, is, if not choline itself, asubstance nearly related to it, perhaps a derivative of choline, andthe latest theory advanced is that it is trimethylamine, a cleavageproduct of choline.38 This is a question quite apart from that ofcholesterol, which all admit is present in cerebrclspinal fluid incases of chemical breakdown of nervous tissues.Another point in relation to choline is whether, when injectedinto the blood stream, it produces a rise or a fall of blood-pressure.This ought not t o be a difficult question to answer.The operativeprocedure is simple, and the preparation of pure choline or of itshydrochloride presents no great difficulties. The majority ofobservers are agreed that the effect is a fall of arterial pressure inaccordance with the original statements of Mott and myself.30 Butthe question has curiously enough raised a keen and bitter contreversy, because certain observers in Russia, Modrakowski andPopielski,40 have persistently maintained that everybody exceptthemselves is wrong, and that the typical effect of an injection ofcholine is to raise arterial pressure, and that the opposite resultobtained by others is due to their having used impure materials.One always distrusts observers who claim for themselves a monopolyin the capacity t o carry out correctly a simple piece of chemicalanalysis or physiological experimentation, and one cannot thereforebe sorry for the wholesome castigation administered to Popielskiand his colleagues by Abderhalden and F. Miiller.41 This is notby any means the first of their papers dealing with the subject, butit is the most thorough, and will in the minds of all reasonablepeople settle the question once and for all.Some of their prepara-tion was sent t o Popielski ih order that he might test the matterfor himself, and he reported that it produced a rise of blood-pres-sure. Unfortunately for Popielski, the specimen sent (by mistake)was an impure one, which according t o him should have produceda fall of blood-pressure. It did produce a fall of pressure inBerlin, and so did the pure specimen. Many strange things have38 C. Dorke and F. Golla, Bio-Chem. J., 1911, 5, 306 ; A . , ii, 212.39 These observers have recently been joined by the following : Z.Berlin (Zentr.Physiol., 1910, 24, 587 ; A., ii, 516) and A. Lohmann (Zeitsch. B i d , 191 1 , 56. 1 ;A., ii, 630).4o Popielski's riiost recent paper will be fouiid i n Zeitsch. physiol. Chern., 1910,70, 250 ; A., ii, 124.Ibid., 1911, 74, 253 ; A., ii, 994.0 196 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.occurred on the Russian frontier, but this transformation surelybeats the record.Manganese and Vanadium as Constituents of Animai? Tissues.-Everyone acquainted with the history of chemistry will rememberthat the element phosphorus was first discovered in an animalproduct, namely, urine. It was not until nearly half a, centurylater that it was found in the mineral kingdom. This discovery inthe eighteenth century evoked as much interest in the scientificworld as the discovery of radium has done in our own day.As arule, however, the discovery of new elements occurs in the inorganicworld, and later on search is made for them in animal tissues, andthe list of the elements present in the latter thus grows in length.The discovery of iodine, however, in 1811 dates from the investiga-tion of se*weeds, and it was not until about twenty years ago thatBaumann showed that it is also present in organic combination inthe secretion of the thyroid gland in animals. The long list ofelements found in animal tissues must now have added to it twomore, namely, manganese and vanadium. The presence of man-ganese in such tissues which had been occasionally noted in thepast was attributed to accident; and manganese, like copper andlead, was therefore supposed to be due to contamination with thematerial used in utensils employed for cooking, etc., or to the useof drugs. No doubt in the majority of instances this is the correctexplanation.Copper, however, we now know is contained in a tleast two physiological proximate principles, namely, haemocyanin,the blue pigment in the blood of many crustaceans and molluscs, andturacin, the red pigment in the feathers of the plantain-eating birds.It now seems equally necessary to include manganese as a normalbody constituent in certain forms of animal life. According t oPiccinini,42 it occurs in varying quantities in the different tissuesof the animal and human organism. It is obtained from the food,but does not disappear when a diet free from it is taken.Theaddition of manganese to the diet is also stated to increase the ironof the blood, liver, and spleen. One would hesitate from thisdeecrrption to include manganese among the normal constituentsof the body; its presence partakes more of the accidental order.and like many poisons, although manganese itself produces noobvious toxic symptoms in these doses, it appears to remain in thetissues, and is excreted with difficulty. But in the case of certainaquatic animals there is a different story to relate. Its presencein the fresh-water mussels or clams, Unio and Anodon, was firstnoted by Bradley in 1907,13 aud in their eggs. His promise to4L Arch. farm. sperim., 1910, 9 ; A., ii, 622.43 J .Biol. Chem., 1907, 3, 151 ; A . , 1907 ii, 567PHYSIOLOGICAL CHEMLSTRY. 197investigate the source of the metal and its physiological meaningwas only fulfilled last year.44 He found that the element can bedetected in most of the organs of the mussel, but is most abundantin gills and mantle. The source of the element is the food theseanimals ingest; and that, of course, is the source of any othersubstance found in the body. They feed on crenothrix and diatoms,which are able to concentrate manganese from its very dilutesolution in the water. I n lakes where the water is very pureneither crenothrix nor mussels are found, nor do they live ifplaced there ; the manganese has probably a respiratory functionin the tissues and blood of these larnellibranchs, much as iron hasin our own blood.No one had previously dreamt that the comparatively rare metalvanadium was a pmsible constituent of animal structures, butHenze 45 has found it in the blood-corpuscles of certain ascidians,Phallusia being the animal he made most of his observations on.These corpuscles are extremely acid t o litmus, and the acid is inlarge part volatile with steam, and probably organic. On exposureto air, the corpuscles turn yellowish-green t o blue; the chromogenof this pigment is soluble in water and in acetone; in time it turnsbrown. On incineration it yields about 15 per cent.of vanadicacid (V,O,). This is just one of those discoveries which impressesthe imagination; even in the well-tilled field of bio-chemistry thereare doubtless plenty of discoveries still awaiting discoverers.PhysioEogicaZ Climatology.-This paper by Professor Osborne, ofMelbourne,40 is the first of what promises to be an instructive andinteresting series.It illustrates the usefulness of long holidays andopportunities for travel. One compensation we have in the migra-tion of some of our younger physiologists to the colonies is that innew atmospheres they see things in fresh lights. The particularsubject treated of in the paper under consideration is the relationof the loss of water from the skin and lungs to the external tem-perature in actual climatic conditions. The usual text-book state-ment that heat lost by radiation and conduction from the skinmakes up the greater portion of the heat lost from the body, isonly true under certain conditions ; an air-temperature equal tothat of the body would reduce this loss to zero.I f the metabolismof the body is constant during rest, and the heat production there-fore is fairly constant too, it follows that if the air-temperature israised, and loss by radiation and conduction consequently lessened,the heat loss due to evaporation must make up the balance; other-44 J. BioL. Chcm., 1910, 7, xxxvi, and 8, 237 ; A., 1910, ii, 731, 979.45 Zcitsch. physiol. Chcm., 1911, 72, 494 ; A., ii, 740.J. Physiol., 1910, 41, 345 ; A., ii, 124‘198 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.wise heat accumulation will occur, and the body temperature willrise.It would be expected, therefore, that the water loss wouldbe a linear function of the air temperature. This simple relation-ship, however, does not occur, and the cause of the perturbationsin the straight line is not clothing, but is more complex; onefactor, at any rate, is t4he humidity of the air, and another is thevelocity of its movement. If the air is dry and in movement, itwill tend to dry the skin, and if body temperature and skin inbibi-tion are to be kept constant, then the metabolism must beaugmented. What apparently does occur is a compromise : theskin loses some of its water of imbibition, and the metabolismundergoes a moderate rise. This explains the unpopularity of theeast wind in N.W. Europe.Another factor is the amount of ventilation via the lungs; thisis increased when the atmospheric temperature is high, and isknown familiarly in the lower animals, as when a dog pants in thesummer time.How the respiratory centre is affected by a highair-temperature is a puzzle, for the body temperature does notrise; possibly the carotid blood may become heated in its passageup the neck.Osborne also found that the carbon dioxide excreted variesdirectly, not inversely, ag the external temperature. The increasein pulmonary ventilation will in part explain this; more carbondioxide is produced from the additional work of the respiratorymuscles, and more is “washed out” from the tissues. There is,further, some indication that the respiratory quotient rises withrising shade temperature.Harvey Sutton found this quotientapproached unity when the wet-bulb thermometer rose in a roomhe could artificially make warm and moist, and made some sugges-tions regarding the relation of this reaction to the preponderanceof carbohydrates in the diets of tropical aboriginnls.This imperfect and hasty outline of the paper will at leastindicate its practical importance, and make us await with interestfurther contributions on the subject from its author.Creatine and 0reatinine.-I had intended at this point to inserta brief review of the somewhat voluminous work on this subjectwhich has appeared throughout the year. Looking through thepapers once more, however, I find little or nothing that throwsnew light on the very puzzling metabolic problem that thesesubstances present.New facts have been elicited, for instance, theindispensability of carbohydrate food for maintaining the normalcourse of creatine-creatinine metabolism, a function which is notexercised, either by fats or by proteins.47 Such facts, however, and.i7 TJ. B. Mendel and W. C. Rose, J. Biol. Chem., 1911, 10, 213 ; A . , ii, 1002PHYSIOLOGICAL CHEMISTRY. 199others (often conflicting) too numerous to mention are difficult tobring into line with each other, or with any general view of the realhistory of these substances in the body. For this reason, as well asexigencies of space, I prefer to leave the subject to some futuretime when the difficulties that surround the subject are more fullycleared up.Th.e Lipoz'ds.-For much the same reasons, I think it would bebetter to omit more than a passing reference t o the lipoids.Theycontinue to exerciw a great attraction for the researcher, althoughthere is some indication that the actual number of papers aboutthem shows a diminution this year. The work done has beenuseful and painstaking, but in the main is directed to the workingout of details; so here again the subject hardly lends itself togeneral discussion. As examples of the nature of the work inprogress, we may take that of Professor Lorrain Smith48 on thestaining reactions globules of fat and lipoid undergo in microscopictechnique; on methods of estimating such substances by the sameauthor; 49 a separation of the lipoids of egg-yolk,50 and so forth.It is not many years back that I devoted a considerable space ofone of my reports to the lipoids, and the subject is obviously onethat can wait further and fuller development in the future.This leaves me free now to take up the last section of my report,as outlined in its opening, and take up seriatim the three subjectschosen there for more extended treatment.Nucleic Acid and NucZeasP-s.In this instance I make no apology for returning to a subjectI have treated at length in former reports.For here a considerableadvance has recently been made, and our knowledge, both of thechemical composition of nucleic acid and of its fate in the body,is increasing by leaps and bounds.A t the risk of wearying some readers who have studied myprevious reports, I will briefly recapitulate what was known atthis time last year, in order to give some degree of completenessto my story.Nuclein is the name originally given by Miescher in 1871 to themain constituent of the nuclei of cells.He recognised that it wasa nitrogenous phosphorised organic substance in union with aprotein. The non-protein constituent of the complex has since beenknown as nucleic acid. Making rather a long jump to a laterepoch, Kossel isolated and identified many of the cleavage produchJ. Path. Bnct., 1910, 15, 53 ; A . , ii, 57.j!' Iijfd., 1911, 16, 131 ; A., ii, 1006.5o Serono and Palozzi, Arch. farm. sperisn., 1911, 11, 553 ; A., ii, 1005200 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of nucleic acid, and he separated out phosphoric acid and certaincrystalline bases, and noted in addition the presence of a carbo-hydrate.The bases Kmel mainly worked at are those which werenamed purine bases by Emil Fischer, and the four principal onesare hyp oxant hine (mono-oxypurine), xanthine (dioxypurine),adenine (aminopurinei), and guanine (amino-oxypurine). A t first itwas supposed that there were four nucleic acids, each of whichyielded a different base.Later other bases were separated out, which are derivatives ofanother cyclic nucleus, namely, pyrimidine.The work of Walter Jones, Levene, Steudel, and others showedthat ordinary nucleic acid yields two bases of the purine group,namely, adenine and guanine, and two of the pyrimidine group,namely, thymine (diketomethylpyrimidine) and cytosine (aminepyrimidone). Other bases when present are due to secondaryreactions.The identity of the carbohydrate was a matter ofdispute, some regarding it as a pentw, others as a hexose. Kosselregarded i t as a hexose mainly because he obtained from nucleina yield of lzvulic acid.Steudel appears to have been the first to present a provisionalbut complete view of the structure of the constitution of thenucleic acid molecule. He thought it consisted of a chain of fouratoms of phosphorus, each of which was united on the one sideto hydroxyl, and on the other to a hexose molecule. Each of thefour hexose groups in its turn was united to a base, a different basefor each hexose group.Almost simultaneously with this work, that of Bang showedthe existence in certain organs of a simpler form of nucleic acid,which yielded on decomposition only three substances, namely,phosphoric acid, a sugar of the pentose group, and one purine base,guanine.This was consequently termed guanylic acid.This brings us to the work of the years 1910 and 1911, and themore chemical aspect of the subject is discussed in a series ofpapers published in the Uerichte by Levene and his colleague^.^^One important point they made out was the identity of the carbo-hydrate; it is ribose, one of the pentoses. Levene and Jacobs 52very successfully defend this view against certain criticisms ofNeuberg on this question. Without going fully into the compli-cated problem of how the linking together occurs, one may givethe main view taken by these workers, and the new nomenclaturethey have introduced.A nucleic acid is designated a m c l e o t i d e ; thus Bang's guanylic51 Bey., 1910, 43, 3150, 3164 ; 1911, 44, 746, 1027 ; A., ii, 96, 408, 510.5'2 Ib'hzd., 1910, 43, 3147PHYSIOLOGICAL CHEMISTRY.201acid, which yields on hydrolysis only one molecule of ribose andone base (guanine), is a, moncmucleotide. As the number becomes2, 3, or more, we get di-, tri-, etc., nucleotides; thus the part ofthe molecule which yields the two purine bases, adenine (CJ35N5)and guanine (C,H,ON,), may be represented by the followingformula :OH H H H/ I II0: P . o . c H , ~ c ~ c - ~ - c H ~ c ~ H ~ ~ ~ 1 OHOH 1 I ~ -- 0 0H H H0: 1.O.CJ3, c I I .C-d--CH*C,H,ON,I \, 1 o H h 3 IOH 0By splitting off the phosphoric acid, what is left are the twocombinations of ribose and base; that is, ribose+adenine andribose + guanine. Such compounds are termed nucleosides ; it isunfortunate that nucleotide and nucleoside are names that are somuch alike, for i t will be difficult to remember which is which.These two nucleosides are named guanosine and adenosine respec-tively. By hydrolysis with acids the bond between the sugar andthe base is dissolved, guanosine yielding guanine and a-ribose, andadenosine adenine and &ribose. These two nucleosides may also bespoken of as aminonucleosides, because the base in each casecontains the amino-group. By the action of nitrous acid the twoaminwmcleosides are converted into the corresponding hydroxy-nucleosides by removal of the amino-group ; thus guanmine yieldsxanthosine (xanthine + ribose) and adenosine yields hypoxanthosine(hypoxanthine + ribose), also spoken of as inosine, another confusingitem in the new nomenclature.It will be noted I have not compli-cated the account of this work by introducing the pyrimidinecompounds of ribose, such as cytidine, that is, cytosine + ribose,about which less is known, but in which the linking is apparentlynot glycoeidic.Passing now to the physiological or metabolic side of the question,we have t o inquire whether within the body disintegrations occurwhich are similar t o those which we have just seen can be producedby chemical reagents.The answer is ((Yes,” and the agents atwork in the body are enzymes, to which one may give the generalname nuclcases.Before describing the details of this aspect of the subject,let us return for a moment to history; but it is only necessary formy purpose to go back to 1909, in which in my report I state202 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.the following to be an outline of what was then known.53 I repro-duce the paragraph almost verbatim.(' The decomposition is accomplished by certain tissue enzymeswhich have been studied in extracts of tissues and organs. Theirdistribution varies a good deal, both in different animals and intheir different organs, but, speaking generally, they are mostabundant in the liver, spleen and kidney.54 The first to act iscalled rwclease; it liberates the purine bases from nucleic acid.The next to come into play are called deamidising enzymes, becausethey remove the amino-group; one of them, adenase, convertsadenine into hypoxanthine (mono-oxypurine) ; the other, calledg m n u s e , converts guanine into xanthine (dioxypurine) ; finally,oxydases step in, which transform hypoxanthine into xanthine, andxanthine into uric acid (trioxypurine).But even this does notbring the long list to a conclusion, for in certain organs (forexample, the liver) in many animals there is a capacity to destroythe uric acid after it is formed, and the enzyme responsible foruric acid destruction, and which normally protects the animal froma too great accumulation of this substance, is called the w'colyticenzyme ."Now this was complicated enough in all conscience, but furtherinvestigation in the light of the new knowledge we now possess ofthe chemistry of nucleic acid has shown that in reality it is morecomplex still.Starting at the beginning, that is, when nucleic acid enters thebody with the food, our first question is how far its disintegrationproceeds in the alimentary canal.Previous work on this questionhas mainly consisted of investigations in vitro. We are able now torecord experiments carried out by the more satisfactory method ofexperiments on the living animal. This was done by E. S. Londonand Schittenhelm,55 who employed dogs with appropriate fistulaefor the purpose. They found that nucleic acid is neither altered norabsorbed in the stomach, but that it is to some extent split upin the intestine; a small amount of purine bases is liberated, butthe major amount of the nucleic acid given is only broken down asfar as the mono-nucleotide or nucleoside stage, and these areabsorbed lower down the intestinal tube. In a later research,66they succeeded in isolating guanosine, and identifying it withcertainty; they, however, agree with Levene and Jacobs, to whose5s Ann.Report, 1910, 170.54 Fresh facts under this heading are contained in a paper by Jnschtschenko,Biochenz. Zeitsch.., 1911, 31, 377 ; A . , ii, 412.Zeilsch. physiol. Chem., 1910, 70, 10 ; A., ii, 52.56 lbid., 1911, 72, 459; A . , ii, 745PHYSIOLOGICAL CHEMISTRY.203work we shall pass immediately, that the final splitting occurs inthe organs and tissues.Levene and Medigreceanu 57 made their experiments in vitro withthe natural juices supplied to them by Pawloff. They found alsothat nucleotides were changed into nucleosides by intestinal juice,but that pyrimidine nucleotides were less affected than guanylicacid (guanine nucleotide) ; the nucleos ides (inmine, guanosine,cytidine) were not affected by any digestive juice.We may therefore conclude that during digestion the totalamount of cleavage is small.This brings us t o actual metabolic experiments and the investi-gation of the action of tissue extracts. Here I have six importantpapers to discuss, all emanating from America, some fromLevene’s and some from Walter Jones’s laboratory.I will takethem in chronological order.The first on the list, “Nuclein Metabolism in the Dog,” isby Levene and Medigreceanu.68 It deals with the effect seen in theurine as a result of feeding on nuclein and some of its cleavageproducts. When nucleic acid is given, 50 per cent. appears in theurine, of which 85 per cent. is in the form of allantoin, and therest as urea. I f thymus gland is given, 17 per cent. of the nitrogenis excreted as allantoin, 5 per cent. as uric acid, and the rest urea.Various purine bases were given, and certain nucleosides, such asinosine; varying fractions of the nitrogen in urea, allantoin,uric acid, etc., were obtained. These results clearly show that inspite of the small change produced in the alimentary canal, thenuclein group of substances are nevertheless broken down intosimpler materials somewhere in the body; it is obvious that thissomewhere must be in the tissues and organs.The same authors69 then proceeded t o investigate the varioustissue jnices, or plasmata, as they term them.It is only necessaryto give a few samples of their results. Plasma of hearbmuscle,liver, kidney, and intestinal mucosa hydrolyse inosine or hypo-xanthosine, giving rise to the free base and d-ribose; bld-serumand pancreas-plasma have no effect. Guanylic acid is hydrolysedby the same plasmata, with the addition of that obtained from thepancreas. Cytidine (cytosine + ribme) was not split by any plasmainvestigated, and the cleavage of nucleic acid from yeast was incom-plete.Such work at once demonstrates that various tissues may actin different ways, and indicates that the enzymes are numerous anddifferently distributed in the organs.s7 J. Biol. Chem., 1911, 9, 375 ; A . , ii, 744.j8 dmcr. J. Physiol., 1911, 27, 438 : A., ii, 303.5y J. Biol. Chem., 1911, 9, 6 5 ; A., i, 410204 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.This view was accentuated in the third paper I have to refer to,this time from the pen of Walter Jones.*O H e regards the use ofthe term nuclease as unsatisfactory if it is understood to mean anenzyme which liberates purine bases from nucleic acid, for thereis no assurance that the enzyme of one gland can decompose thenucleic acid of another organ.Although the nucleotide structureis common to all the nucleic acids, differences occur in the natureand number of their nitrogenous rings, and it would therefore besurprising if one enzyme can decompose them all, for the moreone learns about enzymes the greater appears to be their specificity.Illustrating this, he found that an extract of ox spleen will effectthe decomposition of the mono-nucleotide guanylic acid, but thatpig’s pancreas which is rich in other kinds of nuclease has no effecton this particular nucleic acid.As a further illustration of the multiplicity of the enzymicagent. at work, Jones in his next paper61 considers the case of thedeamidases, and shows that there are a t least four independentones. We must add to the adenase and guanase, which were knownbefore, two others, namely, guanosine-deamidase and adenosine-deamidase.Their actions are indicated by their names; thusadenase converts adenine into hypoxanthine ; adenosine-deamidaseconverts adenosine into hypoxanthonine ; guanase converts guanineinto xanthine ; guanosine-deamidase converts guanosine intoxanthosine. The enzymes acting on the amino-purines are distinctfrom those which act on the aminmmcleosides, because one groupis present in pig’s liver, for instance, and the other is not.The next contribution to the subject takes us back again toLevene and Medigreceanu.62 They accept the work of Jones, andof similar results obtained in Germany by Schittenhelm, and whichcoincides with their own results in regarding the gradual seriesof changes that occur in nucleic acid, as being due to the gradedaction of numerous and specific enzymes, and they classify thenucleases into three groups as follows :(1) Nucleinases, which resolve the molecule into mono-nucleo-tides; these occur in all organs, in pancreatic juice, but not ingastric juice.(2) Nucleotidases, which liberate phosphoric acid, leaving theribose-base complexes (nucleosides) intact.These also occur in allorgans, and in intestinal juice, but are absent in gastric andpancreatic juices.(3) Nztcleosidnses, which hydrolytically cleave the nucleosides6o J. Biol. Chena. 1911, 9, 129 ; A . , i, 410.62 Ibid., 1911, 9, 389 ; A,, i, 698.Ibid., 169 ; A , , i, 410PHYSIOLOGICAL CHEMISTRY.205into their components, ribose, and bases of the purine or pyrimidinegroups. These are absent in all the digestive juices, and in theplasma or tissue juice expressed from the pancreas, but are presentin varying degree in the plasmata of most other organs.I now reach the last paper on the question, and this is a verycomprehensive one by W. Jones and S. Amberg.63 These writersagain emphasise the points already noted relating to the multiplicityand specificity of the enzymes at work. To show the differencesbetween different organ extracts, let us take the following as aninstance. The pancreas and theliver of the pig were both employedto act upon nucleic acid. In the pancreas experiment, guanosinewas one of the end-products, but this nuclemide underwent nofurther cleavage ; adenosine was formed simultaneously, but thiswas deamidised t o form hypoxanthosine or inmine.In the experi-ment with pig’s liver, guanosine was not only deamidised to formxanthosine, but the xanthosine was further split into ribose andxanthine. At least nine enzymes are in this way called into play:(1) Phosphenuclease.(2) Purine nuclease.(3) Guanosine deamidase.(4) Adenosine deamidase.(5) Adenase.( 6 ) Guanase.(7) Xanthosine hydrolase.(8) Inosine hydrolase.(9) Xantheoxydase.We further see that this clears up another difficulty I alluded toin a previous namely, how does hypoxanthine occur inmuscle, seeing that adenase is absent from that tissue? The pro-visional answer given a t that date was that hypoxanthine in thissituation is “ preformed,’’ and is not directly connected withnuclein metabolism at all.We have now another possibility, anda much more probable one, and that is that adenosine is deamidisedto hypoxanthosine (or inwine) by the enzyme numbered (4) on theforegoing list; and this is hydrolytically split so as to yield hypo-xanthine by enzyme No. (8) on the list. Enzyme No. (5) in thiscase never comes in at all.Finally, let me attempt briefly to summarise:(1) Nucleic acids possess a common structure, namely, phosphoricacid combined with a carbohydrate (the pentose named riboae),which in its turn is united with a base.63 Zeitsch. phylsiol. Chem., 1911, 73, 407 ; A . , ii, 823.64 Ann. Report, 1910, 171206 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.(2) They differ from each other by such grouping being eithersingle or re-duplicated.(3) The general term nucleotide is adopted for the phwphoricacid-ribose-base complex.(4) Nucleic acids may be monenucleotides ; for instance,guanylic acid; but more usually the grouping is re-duplicated toform poly-nucleotides.(5) The bases obtainable from poly-nucleotides are adenine andguanine of the purine group, and bases of the pyrimidine group,such as cytosine.(6) I n the case of the pyrimidine basw, their union with riboseis possibly not glycosidic, and is firmer than in the case of thepurine bases.(7) When broken down by chemical reagents, the first changeis the removal of the phosphoric acid, leaving intact the combina-tions of ribose and base.(8) The ribose-base complexes are termed nucleosides ; thus :guanosine = guanine + ribose.adenosine = adenine + ribose.cytidine = cytosine + ribme.(9j The nucleosides may be split hydrolytically into base andcarbohydrate ; or they may be deamidised, and the correspondinghydroxynucleosides obtained; and these in their turn may by hydrolysis be broken up into base and carbohydrate; for instance,adenosine may be deamidised t o hypoxanthosine (also calledinosine), and this in its turn is split into hypoxanthine and ribme.(10) The same cleavages are aocomplished in the body by theaction of tissue-enzymes contained in varying degrees and kindsin the different organs and tissues.As these enzymes are specific,the number which may come into successive play in the decomposi-tion which occurs within the body is extremely numerous.Theseenzymes may be spoken of in a general way as nucleases. Theindividual names they have received indicate the particular act ofcleavage they perform.(11) The nucleic acids in the food are not affected by gastricjuice, and in the intestine such cleavage as does occur is limitedt o their separation into mono-nucleotides, and the partial conversionof these into nucleoslides by the splitting off of phosphoric acid.‘‘ Standard Bread.”“Some gave them white bread, and Borne gave them brown,”indicates the existence of a dilemma which caused trouble in pastages, and still continues to be a burning question. The advocates oPHYSIOLOGICAL CHEMISTRY.207bread made from the whole grain, or a t any rate from flour whichretains the germ, have received support from a section of the dailypress during the year; and the irresponsible writers who haveconsidered it their duty to boom what they have illogically termed“standard bread” are more remarkable for their zeal than fortheir knowledge. The very word ‘‘ germ ” is one to conjure with ;to many minds it suggests the germ of life, a sort of concentratedessence of all that is good. To those, however, who desire a soberstatement of facts rather than a hysterical presentment of crudeideas, I would recommend an article on the subject by ananonymous writer in a recent issue of Science Yrogress.65There is no doubt that the boom has been beneficial to certainmillers, who have been able t o sell at high prices inferior flourswhich would otherwise have been wasted.There is also no doubt that to the majority of people the choiceof white bread or whole-meal bread is altogether immaterial;it is purely a matter of taste t o those who live on an ordinary mixeddiet, and to whom bread is only one of the many articles of foodingested.Experiments on rats such as those published in preliminarycommunications to the weekly medical journals are wholly incon-clusive; still less convincing are the hastily compiled statistics byschoolmasters bitten with the craze.The only logical attitude taken up by a responsible person isthat assumed by Dr.F. hwland Hopkins, and that is that adecision is impossible in the present state of knowledge, and eventhen the decision will only affect those people to whom bread reallyis the staff of life.The homeopathists of the past, as is well known,used to prescribe drugs in such extremely minute doses that anyphysiological action would have been next door t o impossible. We,however, are now acquainted with substances such as adrenalineproduced in the body which produce powerful effects in doses muchsmaller than those of the homeopathists. Such materials mustultimately be formed from the food, so that very minute quantitiesof certain food materials may be important factors in the mainten-ance of health. The germ of the wheat grain is the part which willultimately grow when sown into the new plant, and it is quitepossible, as Dr.Hopkins has pointed out, that there may be certainsubstances elaborated by the living cells of the plant which cannotbe readily synthesised by the animal body. Their quantity cannotbe considerable, and if they are present, and their chemicalnature is entirely problematical, it may be that they arenevertheless of value. This is a perfectly feasible hypothesis,Ii5 ‘* The Ethics of Pootl. 111. Bread.” Scci~iice Proyrc,\s, 1911, 536208 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.and one hopes that some really conclusive experimental work maybe set in hand to test its truth. Those who say that whole-mealbread is richer in protein than white bread are speaking the truth,although the difference is not a large one.They forget, however,that chemical composition is never a criterion in itself of thenutritive value of a food. The nutritive value depends on theamount which is assimilated, and that again depends on digesti-bility, and that can only be determined by actual experiments. Tomost people whole-meal bread is not so readily digested as whitebread is, so that any increase in protein percentage is more thancounterbalanced by increased loss in the fceces. Even supposingall the protein in whole-meal bread was entirely digested and assimi-lated, no one can pretend that the small extra dme of nitrogenousintake can be of the superlative value attributed to it by some;the same end might equally well be obtained by an extra halfslice per diem of white bread.The difference is not a quantitativeone, but, if present, is qualitative, and the important substancein the germ, if there is one, is in all probability not protein innature.A piece of work which illustrates the importance of small amountsof certain food materials in nutrition with another form of food,namely, milk, may be referred to here as a case in point. W. Stepp 66fed mice on milk deprived of its lipoids; they soon died, but theaddition of the alcohol-ether extract to such milk prevented a fatalresult. Addition of the fats alone, or of lecithin or cholesterol tosuch milk did not delay the onset of death. Here, a t any rate, wehave some unknown substance present in quite small quant.ity, whichis nevertheless essential for successful growth and life.I have deliberately avoided as much as possible the employmentof the popular expression “standard bread,” for that term begsthe whole question, and assumes beforehand that bread of a certaincolour and made in a certain way is to be regarded as an idealfood.The use of adulterants in all foods should be prohibited bylegislation, and offenders should be severely dealt with who attemptto purvey on a credulous public any food to which something hasbeen added or from which something has been removed. It appearshopeless, however, in the present state of politics to attempt anylaw-making on subjects which affect the public health.Commis-sions are appointed, and their reports are pigeon-holed for years.The report of the Committee which dealt with food-preservativesten or twelve years ago is still a dead-letter so far ils enactments“The Importance of Lipoids i n Nutrition,” Zeitsch.Biol., ’911, 57, 135 ; A.ii, 1002PHYSIOLOGICAL CHEMISTRY. 209are concerned. The President of the Local Government Boardsession after session fails to bring to fruition his Pure Milk Bill.These questions unfortunately do not excite Party feeling, and sofall into the background, and Dreadnoughts still continue to bebuilt without any steps being taken for ensuring the health of thecoming generation who are to man them.That a standard in white bread is quite as necessary as one inbrown bread has been recently brought before the public by thereport published by Drs.Hamill and Monier-Williams.67 I n relationto the grosser forms of adulteration which they reveal there canbe no difference of opinion that these should be sternly prohibited.Whether bleaching by nitrous fumes is harmful to any seriousdegree is a moot point. There is some retardation of digestion,especially towards saliva and gastric juice, but the amount ofnitrite left in the flour is extremely minute, and in the bread madefrom the flour it is still further reduced.Another anonymous article on this subject in Science Progress (j*has appeared, and its author rather scorns the evils described,especially bleaching, and takes Drs. Hamill and Monier-Williamsto task for condemning such procedure. This I regard as a veryunsafe attitude to assume.Our knowledge of the effects ofbleaching is still in its infancy; the object of the miller is tosupply the public with what they ask for, namely, very white flour,and the consumer runs the risk of the flour being over-bleached,and therefore admittedly harmful, or of obtaining inferior flourmade to look like the best, so that the miller reaps a pecuniaryreward t o which he is not entitled.The striugent laws of t.he United States against the employmentof adulterants of this order meet with my entire sympathy, for ifthey err at all it is an error on the right side, as they prevent theintroduction of even the thin end of the wedge.The following brief extract from a judgment by Mr. JusticeWarrington in a case tried before him two years ago may be ofinterest.The case in question was one between rival patenteesin the matter of flour-bleaching.“Even Dr. Halliburton did not go further as a summary ofwhat he considered to be the result, than that the process of treat-ment by the plaintiff’s invention imposes on the human framejust one more of those extra burdens which the progress of civilisa-tion has from time to time imposed on the human frame. Many67 ‘‘ Reports to the Local Government Board on the Bleaching of Flour and theBy J. M. Hamill and G. W. Monier-See also in a more68 1911, 279.addition of so-called lmprovers to Flour.”Williams.condensed form, J. Rygiene, 1911, 11, 142, 167 ; A . , ii, 1001.Food Reports, No. 12 (Cd. 5613), No. 14 (Cd. 5831).REP.-VOL. VIII.210 ANEUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of us think that there are many modern improvements, the intro-duction of motor-cars, for example, which impose an extra strainon the human frame, but no one would pretend to say that apatent for the invention of a motor-car would not have been auseful invention for that reason. With regard to digestibility,it seems to me it is not a practical objection, and even if it ismade out that there is a scientific and theoretical action on theflour which may be said to be deleterious, there is no evidencethat there is any practical substantial deleterious result of whichI can take account.”That really is the crux of the whole question, and those interestedin public health will have to see in the future that the scientificobjection never becomes substantial and practical, just as someof our public authorities are attempting to minimise the dust,smell, noise, and other discomforts that attend the use of motor-omnibuses.Knowing as we now do the possible dangers whichmight ensue were millers allowed a free hand, it is necessary thatif bleaching is still countenanced a strict watch should be exercisedto keep its use within the limits of safety.Be&- b eri.Here we pass from one of the important questions of the Westto a somewhat similar problem which is mainly of Eastern interest.No hypothesis hitherto advanced with regard to the origin ofberi-beri (the kakkee of Japan) has up till now found sufficientexperimentaJ confirmation to warrant its general acceptance.Thisapplies equally t o the conception of the disease as due to thepresence of hacteria or other parasites, to toxins in the body orin food, or to c‘miasms.” One fact, however, stands out clearly,and is now generally admitted by investigators, namely, that thereis some connexion between the disease and rice. In all thoseEastern countries in which the disease is endemic, every suffererfrom beri-beri is a rice-eater, and conversely European residentswho eat little or no rice do not get beri-beri.During the Russo-Japanese war, very striking illustrations ofthe part played by rice in the causation of the disease came tolight. I take one only. During the siege of Port Arthur, theJapanese army and navy lived under exactly the same conditionswith one exception; in the army the old rice diet was still main-tained, but in the navy a reform had been introduced by addingto the rice a certain amount of either meat or barley.The diseasestill continued to decimate the soldiers, but the sailors escapedalmost scot-freePHYSIOLOGICAL CHEMISTRY. 211The rice consumed in Japan is mainly (‘white rice,” that is, ricefreed from pericarp and husk, and finally polished.A few years ago Dr. S. Kajiura, an officer of the Japanese Navy,worked in my laboratory, and undertook some experiments onberi-beri, or a t least on a very similar disease with characteristicneuritis and nerve degeneration, which can be artificially producedin fowls. These are naturally not the first experiments performedin this way, but exception has been taken to the results previouslypublished, because they were obtained in a possibly (‘ infected ”locality.Whatever objections there may be to King’s College, it,has the advantage of being free from any suspicion of harbouringberi-beri surreptitiously. The fowls fed on the white rice diedwithin a few weeks with the usual symptoms and postrmortemappearance of beri-beri.69 Kajiura in conjunction with Rosenheimhad previously made a study of the nature of the proteins in rice,7Oa cereal which, curiously enough, had escaped any previous examina-tion of the same kind; among the most noteworthy of their findingsthey ascertained that rice almost completely lacks a protein solublein alcohol, similar to the gliadin of wheat and rye, or the hordeinof barley.Thinking possibly that the absence of this protein mightexplain the harmful effect of an exclusive rice diet, they fed someof the birds on rice + hordein, and rice + gluten ; other animals hadadded to their diet calcium carbonate and calcium phosphate inorder to test the hypothesis advanced by others that lack of calciumor of phosphorus might be a t the root of the matter. But in nocase did they succeed in appreciably delaying the onset of death.Fowls fed on barley, however, showed no signs of the disease. Theexperiments were not sufEciently numerous perhaps, for Dr.Eajiura, had t o return to Tokio, but so far as they went theynegatived the suggestion that the lack of a gliadin in rice isresponsible for the production of beri-beri.With the small space still a t my disposal, I cannot attempt areview of the huge literature that has now centred around what isa national question for the Japanese.This will be found in certainpublications issued during the year by the Japanese Governrn~nt.~~I shall only deal, and that briefly, with three papers. The firstF9 Iiajiura. and Rosenheim, J. Hygiene, 19’10, 10, 49 ; A., 1910, ii, 635.7u Proc. physiol. SOC., 1908, liv ; J. Physiol., 36 ; A., 1908, ii, 317,71 “ lllitteilungen der 13eri- t!eri-Studien Kornmission,” Tokyo, 1911.Thispalm contains nnmerous references to other authors.The fullpaper will be published in the Bio-Chewa. J.“ Sanitiits-statistik der Japanischen Armee mit besonderer Beriichsichtigung der Beri-Beri inderselben,” Tokyo.‘‘ Japan und seine Qesundheits-pflege,” by Bintaro Mori, Tokyo, 1911. The last-named book treats of many othersubjects in addition to beri-beri and is a niost interesting work on Japanese history.‘ ‘ Kriegsministerium,” 1911.P 212 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of these deals with analyses of rice, and the economic value ofrice in the tropics; it is only indirectly related to the subject weare discussing, and an abstract has already appeared in ourJournal.72 The second merits .longer notice, because i t does, Ithink, bring us nearer to the solution of the question, and iswritten by two of our own countrymen working in the MalayStates.73 They find that it is the removal of the “polishings” ofthe rice that produces the harmful effects. The natives of theMalay peninsula who consume unpolished or slightly polished ricedo not suffer from beri-beri, but those who take polished rice do.Fowls’ fed on polished rice develop a form of polyneuritis analogousto beri-beri, whereas those fed on unpolished rice remain healthy.I f the polishings removed from the rice are added to polished rice,fowls fed on the mixture also remain healthy. The harmfulinfluence of white rice is not due to a poison developed in itafter milling, but to the removal of some substance of high physic+logical importance essential to the maintenance of health.The estimation of total phosphorus in any given rice indicatesthe extent of the milling or polishing to which it has beensubjected, and therefore of its power in producing disease. Thepolishings are much richer in phosphorus than the part of thegrain left behind. Rice containing 0.4 per cent. or more of P20,is safe.The essential substance or substances are still unknown ; theyare probably small in amount, but whether they act by renderingother constituents of the diet available for nutrition, or whetherthey are themselves the nutritive material necessary for nerve-tissues is a t present a matter of conjecture. The polishings arenot only richer in phosphorised constituents, but are Qomewhatricher in the alcohol-soluble protein than the polished rice. Theprotective substances, as they may be termed, are destroyed byheating the unpolished rice to 1 2 0 O . The fats contained in theperipheral layers of the grain are of no value as a protectionagainst polyneuritis. The protective substances are soluble in0.3 per cent. hydrochloric acid, but phytin, which comprises 32.5per cent. of the substances so soluble, is without value as a protec-tive. The protective substances are soluble in 91 per cent.acidulated alcohol, and exclusive of dextrose amount to not morethan 11 per cent. of the polishings, and not more than 1 per cent.cf the original grains. In this fraction the alcohol-soluble protein72 Arm and Hocson, Bioc7ietn. Zeitsch., 1911, 32, 189 ; A . . ii, 625.73 “ Studies from the Institnte for Medical Research, Federated Malay States,”No. 12. “The Etiology of 1Seri-Beri,” by Henry Fraser and A. T. Stanton.Singapore, 1911. 89 1)ag~’sPHYSIOLOGICAL CHEMISTRY. 213and compounds of calcium, magnesium, and phosphorus areincluded.This narrows down the search very considerably, and one hopesthat i t may not be long before the protective substance is fullyidentified, although one is naturally cautious in prophesying ; suchmaterials one knows by experience are often very elusive.The third and last paper to which I have to refer has beenpublished since the foregoing paragraphs were written, and containsan important fulfilment of the hope just expressed.74 Funk showsthat the protective substance present in the polishings and absentfrom polished rice is present only in minute amount, probably notmore than 0.1 gram per kilo. of rice. It is an organic base, anda crystalline nitrate was prepared from it, of which an elementaryanalysis was made. The figures are, however, given with caution,as the supply of materiaJ was too small for duplicate analyses. Thecurative dose of this material wits found to be extremely small.I f there is any value in arguing from analogy, it is quite possiblethat the outer portions of the wheat grain may also contain somematerial of special importance.W. D. HALLIBURTON.74 “ The Chemical Kature of the Substance which Cures Polynearitis in BirdsBy Casitnir Funk. J. Ph,ysioZ., 1911, 43, induced by a Diet of Polished Rice.”395