PHYSIOLOGICAL CHEMISTRY.STEADY progress is the key-note of the work in PhysiologicalChemistry which has been published since the date of last year’sreport. It seldom happens that an annual writer is able t o pointto any great discovery made in the preceding twelve months, andit is not my good fortune to be able t o chroniclei any such importantevent this year. Most discoveries are made so slowly, and pieceby piece, that it is difficult to assign any date a t all t o them, andthe surest knowledge is always proportional to the pains taken torender each piece accurate. Ehrlich’s views, for instance, on im-munity problems furnished investigators with a brilliant and fruit-ful stimulus to further work, and the steady flow of researches onthese lines which still continues shows that the stimulus is stilleffective.But the general theoretical results are a t present difficultto see, and it is impossible to bring anything) in the w-ay of order outof the apparent chaos. Physical chemistry, again, has its physio-logical applications ; it has enabled us to understand somethingmorel than we previously did about the osmotic processes in thebody; it has taught us that the action of salts must be viewed inthe light of the action of ions; and it has reduced the investigationof even such obscure questions as ferment action to almost mathe-matical precision.1 But here again the time is not ripe for general-isation; the physical chemists have many differences of opinion onquite fundamental questions to settle first, and until these arecleared away, the physiologists must be content to wait for the fullbenefits they expect from this new branch of science.It will therefore not be to questions of this nature that I shalldevote the bulk of what I have t o say, although they have, so far asspace is concerned, occupied so much of the Chemical Society’sJournal and its abstracts.I imagine further that it is not theobject of such a report as this t o epitomise still further the epi-tomes which have monthly made up the bulk of the Journal, butSee, for instance, E. F. Armstrong’s “Studies in Enzyme Action,” Nos. VIIand VIII of which have recently appeared (Proc. Roy. Xoc., 1905, -6, 76, 592, 600 jAbstr., 1906, i, 127, 125).Q 228 ANNUAL REPOItTS ON THE PROGRESS OF CHEMIS'I'RY.rather t o give the writer, who happens in this case t o be also auabstractor, an opportunity to enlarge upon certain aspects of thescience with which he happens to be more familiar, and t o exercisethat right of comment which is denied to him when he merelypresents an abstract.I shall naturally take the abstracts as ths foundation of suchremarks, and shall endeavour to select those subjects which appeart o be most profitable for discussion.Prot eid Chemistry and P r o t eid Me tab olism.This question still stands, and probably for many years to comewill continue t o stand, pre-eminent in its importance t o the workerswho apply themselves to the chemical side of biology.Nomenclature.-At the outset we meet with a difficulty inthe very names applied t o the heterogeneous groups of substancesincluded under the word Proteid.The difficulty has become anacute one for teachers and students, so various are the terms thatlare used by different writers. A committee has consequently beenappointed t o consider " Proteid Nomenclature," and physiologistsand chemists have sat in conclave t o formulate something they hopewill be acceptable t o all. Although their work is not yet concluded,it may not appear premature to state their main decisions.Our knowledge of the chemistry of the albuminous substances isslowly progressing under Emil Fischer's leadership, and this willno doubt in time enable one t o present a classifica,tion on a strictlychemical basis. But until that time arrives, we must be contentvery largely with the artificial classification (on the basis of solu-bility and so forth) which has hitherto prevailed.The classificationsuggested must therefore be regarded as a provisional one, which,whilst it retains the old familiar names so far as possible, yet at-tempts also t o incorporate some of the new ideas.The general name recommended for the whole group is that ofProtein. It is a t present so used in America, and to some extentin Germany, and has been definitely accepted by Fischer in thevolume of his collected papers on the subject which has recentlyappeared. The word has the advantage of admitting of the derivedwords, protease, proteose, &c., and it has, after all, the ring offamiliarity.The sub-classes, beginning with the simplest, would be asfollows : -1.Protamines.-These yield a comparatively small number ofamino-acids as their cleavage products, and are instanced by suchsubstances as salmine and sturine derived from the sperm of fishes229 PH Y S I 0 LOG I C AL C HE MI S TRY.Their most abundant cleavage products are diamino-acids ; someprotarnines yield, for instance? over 80 per cent. of their nitrogenin the form of arginine.2. Histones.-Tbese yield a larger number of amino-acids, butnot so many as those in the next classes. They have been separatedfrom blood corpuscles, and are peculiar in being precipitable fromsolution by ammonia. Classes 1 and 2 probably shade insensiblyinto one another.3. Albumins.4.Globulins.The albumins and the globulins differ from one another in theirsolubilities, the globulins being more readily salted out ” than thealbumins. They comprise the greater number of native proteins,and all possess the character of being coagulated when their solu-tions are heated.5. Sclero-proteins.-This perhaps is the most heterogeneous groupof the series; i t includes the gelatin and keratin members. Theprefix of the new word indicates the skeletal origin and often in-soluble nature of these substances. They have in tha past beencalled albuminoids by physiologists, but this word is ambiguous,and is used, and probably will continue to be used, by manychemists as equivalent to protein.Theprefix nucleo- frequently used in relation to these substances is bothincorrect and misleading.7.Conjugated proteins.-Here the protein molecule is united toa “ prosthetic ” group. The principal varieties of these are thenucleo-proteins, the gluco-proteins ( e . 9 . mucin), and the chrorno-proteins (e.9. hznioglobin).Coming next to the products of protein-hydrolysis (a term pre-ferable to proteolysis), the Committee recommend that these be clas-sified as follows:-1. Meta-proteins.2. Proteoses.3. Peptones.4. Polypeptides.Meta-protein replaces albuminate (acid-albumin, alkali-albumin).The termination ate implies a salt, and so is objectionable. Thesefirst products are, moreover, obtainable from both albumins andglobulins, and the prefix rneta- is an indication of comparativelyslight chemical alteration.The proteoses form the next stage ascleavage continues, and then come the peptones, a household wordvery unlikely ever to disappear from chemical literature. The termshould, however, be restricted t o those further products of hydrolysis6. Phospho-proteins.-This is the vitellin-caseinogen group230 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.which cannot be salted out from solution, but which, nevertheless,still give the biuret reaction.The polypeptides are still further on the down-grade; althoughmost of those we are acquainted with are synthetical products whichFischer has prepared by linking amino-acids together, some havebeen discovered as a result of digestive cleavage, and no doubt arethe immediate precursors of the final cleavage products, the amino-acids.It should, however, be noted in conclusion that this classificationi s mainly applicable to proteins of animal origin.The vegetableproteins may be arranged under the same main headings, althoughit is doubtful if a real and complete analogy exists in all cases. Thecleavage products of the vegetable proteins are in the main thegame as those of animal proteins, but the quantity of each yieldedis usually different; for instance, vegetable proteins, as a rule, givea very much higher yield of glutamic acid than do those of animalorigin. Further, there are certain vegetable proteins which havehitherto been regarded as peptones, but which do not give the biuretreaction. It seems impossible at present to bring exceptional sub-stances of this kind into any general classification, and the sameis true for those curious vegetable proteins, such as gliadin and zein,which stand apart from all other members of the group in beingsoluble in alcohol.Emil Fischer’s book, which has just been mentioned, will provea, boon to all of those who are grappling with the chemistry of theproteins, for in it, are collected his numerous memoirs on the subjectdown to the end of 1905, together with those published by his col-leagues.One searches in vain on the title-page for the legend Vol. I.But it can only be the first of a series, and already there is a goodlysupply, mainly from the pen of Abderhalden, for the second. Thisis just one of the cases, alluded to in the opening paragraph of thisreport, in which details are being steadily collected.The proteinsone by one are being taken to pieces, and the final cleavage pro-ducts identified and estimated. One cannot but admire the patienceof a worker who thus gradually plods through this routine workin order to pave the way to the final generalisation which will comein the future. Much the same sort of thing is being done in rela-tion t o the nucleic acids by Levene. The forthcoming index willbe a more trustworthy guide to all these numerous papers thanm y amateur attempt of mine to forestall it. In spite of all the hardwork involved in researches of this nature, Abderhalden has foundtime to write a, general TextrBook of Physiological Chemistry, whichis a most admirable compendium of up-to-date information, and in itsstyle rmalls that of Bunge, Abderhalden’s former master.Two nePHYSlOLOGICAL CHEMIS'L'ICY. 231books have also appeared on the Proteins, each of which has itsspecial merits; the first of these is by Dr. Schryver (Chemistry ofthe Albumens, J. Murray), and deals mainly with the purechemistry of the subject. The other, by Dr. Gustav Mann(Chemistry of the Proteids, Macmillan), started as a translationof 0. Cohnheim's work, but ended in a volume twice the size ofits German prototype. It contains a mine of references to originalresearches, and is chiefly interesting to those who deal in specula-tions of a physico-chemical kind.Globulins,--The distinction between globulins and albumins isone which is mainly based upon differences in solubility; the generalreactions of both classes are identical, and the opinion has beenfreely expressed of recent years that the differences are purely arti-ficial. This idea was first brought into prominence by Starkesome years ago, when he showed that by quite simple means theyield of globulin in such fluids as blood-serum can be increased a tthe expense of the albumin.It was further emphasised by thediscovery of certain substances termed pseudo-globulins, which, al-though they differ from albumins in the readiness by which theycan be salted out of solution, nevertheless possess the albumin-likecharacter of being soluble in water. Moll takes much the sameview as Starke, and contends, in his most recent paper,l that thenaturally occurring pseudo-globulin of horses' blood is identicalwith that prepared artificially from the crystallised albumin of thesame blood.Another paper embodying the same notion has beenpublished by Sikes,% in which he shows that, in the absence of bac-teria, the globulin of albuminous urine (especially if the fluid isalkaline) increases and the albumin diminishes when the urine iskept.But in all these cases the test used for the globulins has beenthat of solubility; there has been no attempt to ascertain whether,when an albumin changes into a supposed globulin, there has beenany chemical alteration. When we consider that solutions ofalbuminous materials are not true solutions, but colloidal solu-tions, and when we realise that the phenomena of " salting out "are properties that are shared by other colloids, it is not difficultto understand that slight dzerences of temperature, reaction, andthe like will cause a material labelled albumin to undergo smallchanges of solubility which cause it to be precipitable by reagentswhich under more normal circumstances precipitate globulins only.The molecules of a protein are unstable ones, and it is possible toimagine further that accompanying the changes of solubility someslight intramolecular changes of a chemical kind may take placeBcitr.Cheni. Physiol. Pcith., 1905, 7, 311 ; A b s t ~ . , 1906, i, 53.J. PhysioZ., 1905, 33, 101 ; Abs.fr., 1905, ii, 843232 ANNUAL IiElWKl'S ON THE PHOOKESS OF CHEMISTRY.as well.But it is not possible to imagine that any profoundchemical change can occur, and there would be a very profoundchange indeed if an albumin were in very truth transformed intoa globulin. For Abderhalden has shown that the proportion ofthe amino-acid cleavage products in typical globulins differs veryconsiderably from that obtained from typical albumins, andfurther that the difference is not merely quantitative, but qualita-tive also; for instance, the albumins do not yield glycine, whereasthe globulins do. The difference between albumins and globulinsis thus a real and fundamental one. The lessons we should reallydraw from such work as that of Starke, Moll, and Sikes are, first,that it is unwise to rely on solubility tests in any attempt t odistinguish between albumins and globulins, for solubility is avariable quantity ; and secondly, that the statement that albumincan be transformed into globulin cannot be accepted unless sup-ported by chemical analysis.A globulin, then, is a distinct entity, and although Hardy sur-mises that the globulin of blood-serum is formed by the decom-position of a more complex protein there, he has neverthelessselected it as the substance upon which to perform some very re-markable experiments in his study of colloidal solutions. The paperhe has written1 is a complex and highly technical one.In brief,he shows that globulin is an amphoteric electrolyte, and thatglobulin salts ionise in solution. If acid is added, the protein mole-cules assume an electro-positive character, and in the electric fieldthey move towards the cathode; if alkali is added, they assumean electro-negative character and move towards the anode; but inneutral solutions there is no movement, and, moreover, in normalserum " ionic globulin " is absent.The same results have also beenobtained by Pauli.2 Pauli goes further than Hardy by askingwhether the electrical charge of proteins may not possibly explaincertain physiological phenomena in connexion with protein chem-istry and assimilation, immunity, histological staining reactions, andeven fertilisation. It is easier to ask such questions than t o answerthem. One is on safer ground if one merely records the facts a t pre-sent, and the main result that a protein may act amphoterically isintelligible if we accept Fischer's view that every protein is a longchain of amino-acids, for every link of the chain is capable of actingeither as a base or an acid according as its acidic or basic groups arecalled into play.I n connexion with Hardy's work, the paper that follows it byJ. PhysioZ., 1905, 33, 251 ; Abstr., 1906, i, 121.Reitr.chern. Physiol. Path., 1906, 7, 531 ; Abstr., 1906, ii, 180 ; Xaturw.Bundsch., 21, 3, 17 ; Abstr., 1906, i, 545PHYYlOLOOlCAL CHEMISTRY. 233Mellanbyl should be read. This also emanates from Cambridge,and deals with globulins; the treatment of the subject is on ratherdifferent lines, but is based on physico-chemical conceptions.Ash Constituents of Protein.-The only other physical paper towhich I shall allude is rather an important one by Bayliss.% Igave a very full abstract of it a t the time it appeared, and so itwill only be necessary here to refer to its physiological side.Theash constituents of proteins have always been somewhat of a puzzle,but Bayliss appears to have obtained the correct solution of theproblem. They are not in chemical combination ; they are not merelyin mechanical admixture, but they are in a condition midway be-tween these two extremes, and are adsorbed in the same way thatmany dyes are adsorbed by fabrics. The main experiments weremade with gelatin, and the curve of electrical conductivity of suc-cessive distilled water extracts of gelatin is, as in the case of dyes,a hyperbola.Such a curve only approaches the axis (that is, zeroconcentration) asymptotically, or, in other words, it is impossible t owash out all the electrolytes, except by an infinite number ofchanges of distilled water, each washing removing a less percentagethan the previous one. I f such gelatin is again placed in solutionsof electrolytes, it again adsorbs them in a non-ionised condition.Adsorption is doubtless an important factor in many physio-logical processes. I n the staining of histological preparations, theevidence is in favour of the adsorption theory, and here the partplayed by electrolytes must also be taken into account I f electro-lytes are split off from living cells on death or injury, it is clearwhy such cells readily take up acid dyes; moreover, since electro-lytes are unnecessary when the substance to be stained is electro-negative, it is clear why living cells can be stained with basic dyes.The affinity of the Nissl granules of nerve-cells for basic dyes isabolished by previous treatment with neutral salts (Mayr 3), andthis is also in accordance with Bayliss’s results.It is quite certain that there is no universal law in such matters,and in the staining of cells there are cases of true chemical com-bination; and such results as those of Mncdonald * with injurednerve-fibres and neutral-red are difficult to explain by the adsorptiontheory; evidently here other factors have to be considered.Thisis freely admitted by Bayliss, who does not, like so many workersa t a new idea, seek to make it explain everything that was obscurebefore.He certainly puts forward the view that the action be-] J. Physiol., 1905, 33, 335 ; Abstr., 1906, i, 122.Biochem. J . , 1906, 1, 175 ; Atstr., 1906, ii, 344.:% Beitr. chenz. Physiol. Path., 1906, 7, 548 ; Absh.., 1906, ii, 182.Proc. Physiol. SOC., 1905, xsxvii, lxvi ; J. Physiol., 32 ; Abslr., 1905, ii, 405,545234 ANNUAL REPORTS ON THE PROGRESS OF' CHEMISTRY.tween toxins and antitoxins is possibly adsorptive, and that theunion between an enzyme and a colloidal substrate may be of thesame nature, but he does not try to make adsorption explain theuniverse.A bsorption of Protek.-Passing from adsorption to absorption,we reach surer ground, and proceed to deal with matters of morepractical interest.The old view that proteins are absorbed as pep-tones and proteoses, and that the fact of these not being discoveredin the circulating fluids is due to their being resynthesised in thecells of the living membrane of the intestine into proteins of thealbumin-globulin type, has now been definitely abandoned. Pro-teins are absorbed as amino-acids, and evidence of any specialsynthetic formation of proteins by the epithelium of the intestineis lacking (Schryver,l Leathesl); the greater part of these arenever built into living protoplasm a t all, but they are rapidlyconverted by the liver cells into urea, and this finds an easy exitfrom the body by the urine. The small amount that is needed fortissue repair is doubtless picked out of the blood and lymph by thevarious tissue-cells, and i t is there that protein synthesis takesplace, just as it is there also where internal respiration occurs.Inhis early experiments in relation to this problem, Leathes at-tempted to study it by examining the blood leaving isolated loopsof intestine in the interior of which the cleavage products had beenplaced. The loops were perfused with defibrinated blood, butin these circumstances no absorption whatever occurred, andthe intestinal epithelium underwent degenerative changes. De-fibrinated blood is not normal blood, and toxic effects have beenpreviously described when it has been used in other experiments(Brodie2). It was therefore necessary to deal with the intactanimal, in spite of the greater experimental difficulties of searchingfor absorbed products when diluted with the whole volume ofthe blood; and this is what Leathes3 in conjunction with Cath-cart has now done.They found that during absorption ofprotein cleavage products there was no increase in the coagulableproteins of the blood, but that there was a small but distinct risein the amount of non-protein nitrogen. A superficial observermight ask, Why was the rise only a small one? but the answer isobvious. Absorption is a slow process, and the amount of amino-acids absorbed is diluted with the whole volume of the blood, andfurther, as soon as it is absorbed, or shortly afterwards, it is re-moved from the blood. Many years ago Kuhne argued that theamount of amino-acids in the intestines a t any particular momentduring digestion is so small that complete protein cleavage cannotSee last year's Rrport, p.214. J. Physiol., 1900, 26, 48.3 Ibid., 1906, 33, 462 ; Abstr., 1906, ii, 181PHYSIOLOGICAL CHEMISTRY. 235be considered to occur to any great extent. He lost sight of thefact that the amino-acids in the intestine were not formed forthe purpose of accumulating there, but for absorption. So withamino-acids in the blood, they are not absorbed in order to bestored in that fluid, but are removed from it by the tissue-cellsand dealt with there, being either assimilated into protoplasm, orchanged and a t last discharged as waste material by the kidney.Since then Howell1 has, by a somewhat different method, beensuccessful also in isolating the amino-acids of the blood, especiallyafter feeding; smaller quantities of them are also present in thelymph.The Amount of Protein in Diet.-We are thus led in logicalsequence again to consider the important practical question of thenormal daily requirements of a man in so far as the protein inhis food is concerned.As is well known, it is Prof. Chittenden ofYale who is mainly responsible for raising the question, and whilstall sympathise with him in his crusade in favour of temperancein food as well as in drink, and many may confess that in thepast they have sinned and eaten too much, it is not surprisingthat his extreme views have been seriously challenged, and thatmany are asking now, would it not be equally unwise to eat toolittle? In deciding whether the Chittenden diet is one which fallsunder that description, there is a great deal more to be done inthe way of accumulating data and performing experiments beforeany decisive answe: can be given.Here experiments on animalsare not very conclusive, for if the vegetarian can point to the oxas an instance of a strong beast which thrives on diluted proteinnutriment, the meat eater can immediately point to the lion asanother vigorous animal who derives his strength from a richlyalbuminous diet. It is not, however, such a long way from theJapanese to the average European, and here accurate data are sadlyneeded. We do know that since the Westernising of Japan hascommenced, the diet of that country has altered also, and the recentprowess of the Japanese has been, in fact, accounted for by thosewho know the country by the more liberal supply of nitrogenousfood which they now ingest.A t the meeting of the British Association last summer a t York,the physiologists and economists combined to discuss this matter,and a t the Toronto meeting of the British Medical Association inAugust, the physiologists united with the doctors in a most interest-ing debate on the same subject.A t the last-named meeting wehad the advantage of listening to Prof. Chittenden himself, andalthough he was ably supported by Dr. Folin, the majority of thePmer. J. Physiol., 1906, 17, 273236 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.speakers were against his views, and doubted whether the mhimurnwas also the optimum.As an instance of the kind of experimental work which is stillnecessary, we may take that performed by seven physiologists a tUniversity College, London.1 They took their ordinary diet, andestimated the nitrogen of their urine.The total nitrogen excretedvaried from 9.6 to 16.5 grams daily, and, speaking generally, theheavier men excreted most. The influence of body weight as ;Lfactor is one which is often lost sight of, and Chittenden himselfis not a heavy person. The relation of uric acid to this was foundto be comparatively very constant, although that is somewhat of aside issue. Taking the nitrogen excreted as a measure of the proteiningested, the average intake of the seven physiologists would be93 grams daily, an amount not much below the usual Voit dietary.Atwater’s standard is 125 grams daily, and in workhouses andprisons it varies from 134 to 177 grams (see Rowntree’s Poverty,a study in Town Life).But the last-named figures are reckonedfrom bought food, and so the comparison is not quite fair, for theamount of waste is usually considerable in public institutions.Let us now turn to the question of why the minimum is notalso the optimum. Nature, as a rule, does not work in minimums,and Leathes puts it very well in his book when he says it is notconsidered unphysiololgical t o take a diet which will yield morethan the minimum of fzecal refuse, and he calculates that the dietprovided for an infant by nature in the shape of milk is, evenallowing for growth, ten times richer in protein than the require-ments of its endogenous protein metabolism would make apparentlynecessary.There is probably a real need for an excess of protein beyond theapparent minimum. I n diamond mining a large quantity of theblue earth of Kirnberley must be crushed to obtain the preciousstones.It probably is the case that among the’ many cleavageproducts of protein the majority may be compared t o this wasteearth, and we get rid of them as quickly as possible in the excre-tions, but some few may be unusually precious for protein synthesisin the body, and that in order to get an adequa,te supply of these, acomparatively large amount of protein must be ingested.It doesseem as though the large size of the liver (the riddle of the body, asLeathes terms it) is for the express purpose of dealing with thelarge amount of nitrogenous waste, much as the great capacity ofthe rectum enables the body to grapple with a large amount of fzcalrefuse.Such arguments are of more value than those so often used byPTOC. Physiol. Soc., 1906, x; J. Physiol., 34 ;?Absh*., 1906, ii, 463PHYSIOLOGICAL CHEMISTRY. 237physicians when they say that the intake of protein is for thepurpose of supplying the body with “reserve force.” Reserveforce is just one of those phrases that sound so satisfactory, butwhich it is very difficult to define. In the case of carbohydrates,we have a reserve force in the shape of a storage of glycogen; in thecase of the fats, the same is true, and the reserve is stored in theadipose tissue, but we know little or nothing of a storehouse forprotein, for the amount ingested is usually dealt with and disposeldof within a few hours after it is taken into the body.Pfliiger andhis pupil W. Seitzl have, it is true, suggested that the liver is astorehouse, not only for carbohydrates, but for proteins also, andhave supported their views by observations, partly chemical, partlyhistological, on starved and fed animals, but the idea has not a tpresent met with universal acceptance. Others have supposed thatprotein storage may occur in the muscles, a t any rate in someanimals. Be that as it may, the term reserve force is not one tobe wholly scoffed a t ; i t is not entirely meaningless, and it is after allan undoubted factor in the resistance of the body to fatigue anddisease. It is a matter of common observation how much differentpeople vary in “ stamina,” as it is sometimes called.This, in part,depends on the condition of the leucocytes or phagocytes, in parton the opsonic power of the blood-plasma, and in part on otherfactors less fully understood. It may be that the fresh supply ofprotein stimulates and activates such protective mechanisms in thebody, and certainly it is a practical fact that good feeding enablesthe body (as in tuberculosis) to repel and neutralise the deleteriousagents which produce disease. Each leucocyte may every dayundergo very slight wear and tear, but it will be more likely t oreceive the ‘‘ stitch in time” i f an abundant supply of repairingmaterial is in its neighbourhood.Some kind of attempt has already been made to work out theidea as to which of the Bausteine (to use the German phrase) ofthe protein molecule are so specially valuable for the synthesis ofprotein.The vegetable proteins do not appear to be so nutritious,t o use the popular phrase, as those of animal origin, and thisdoes not seem to be wholly due to the fact that they are not soreadily digestible. F o r are the vegetable proteins after all the sameas the animal ones? Work on their Bausteine seems t o answernd when we consider, for instance, their high yield (often over30 per cent.) of glutamic acid.The same note is also struck by twoBaltimore physicians (Lewellys Barker and B. A. Cohoe)2; theypoint out that certain articles of diet will “agree” and othersPJiiyer’s Arettiv, 1906, 111, 309 ; Abstr., 1906, ii, 241.J. Biol. Chenz., 1906, 1, 229 ; Abstr., 1906, ii, 102238 ANNUAL REPORTS ON THZ PROG€03SS OF CHEMISTRU'," disagree )' with people. On the supposition that this may be duet o the distribution of the nitrogen, they made determinations ofmono-amino-nitrogen, di-amino-nitrogen, &c. , in various foods (veal,pork, sirloin, chicken, fish, &c.), and have given their results ihtables. The differences are very striking, but their ultimate valua-tion is for the future. Still, this again is the sort of work whichmust be done before our knowledge can be based on the bed-rockof experiment.At present we can therefore only make a rough guess as to whichof the Bausteine are the diamonds; but it does appear as thoughphenylalanine and its near relative tyrosine were such; they arecomparatively scanty, and it is known that on injection into theblood stream they do not reappear as urea in the urine.We furtherknow that proteins which yield no tyrosine, such as gelatin, are ofinferior value as food. Gelatin is also destitute of the tryptophanradicle, so perhaps tryptophan is particularly useful too; and iftyrosine and tryptophan are added t o a gelatin diet, the animalsfed on it thrive better than those whose sole nitrogenous food isgelatin on1y.l Histidine and pyrrolidine have been also suggestedas being in the same category, but there again we must awaitfurther information.A critical examination of Chittenden's experiments and conclu-sions has recently issued from the pen of F.G. Benedict.2 Bene-dict's training in the Atwater laboratory would naturally prejudicehim against a revolutionary doctrine ; still, his objections are serious,and will have to be refuted before Chittenden and his comradescan urge their case successfully. But there are other subjects thatpress for consideration, and so I will be content with referringreaders to the abstract I recently supplied t o the Journal, or stillbetter to the original paper, which will amply repay perusal by thoseinterested in the subject.Protein Decomposition Products.Amino-acids.-Some interest hascentred round the question whether amino-acids occur in normalurine, and the introduction of naphthalenesulphonic chloride as areagent for their detection has rendered such an investigationfeasible. It seems to have been established that a minute amountof glycine and possibly of some other amino-acids is normally pre-sent (Embden and Reese,3 A. Lipstein: G. Fors~ner,~ Abderhalden1 Similar experiments have been made on yonng animals by Hopkins and MissWillcock (J. Physiol., 1906, 35, 88), in relation to the maize protein called zein.Zein contains no tryptophan. Zein plus tryptophan maintains growth.2 Amer. J. Physiol,, 1906, 16, 409 ; Abslr.., 1906, ii, 689.3 Beitr. chem. Physiol. Path., 1905, 7 , 411 ; Abstr., 1906, ii, 108.4 ?bid., 327 ; Abstr., 1906, ii, 109.6 Zeit.physiol. Chem., 1906, 47, 15 ; Abstr., 1906, ii, 243PHYSIOLOGICAL CHEMISTRY. 239and Schittenhelm,l F. Samuely,2 Wohlgemuth and Neuberg 3), butwhether this has any physiological significance is uncertain; theview expressed by the majority of observers is that the amountis really a negligible quantity. The importance of the inquiryarises from the study of pathological urine. I f , for instance, theamount is increased in gout, we should be provided with anotherstep in the ladder of knowledge concerning what is still an obscuredisorder. Here, unfortunately, the observers disagree, some de-scribing an increase in gout,, leuczemia, and pneumonia, but othersstating that the variations are within normal limits.A still more wide-reaching inquiry concerning the fate of amino-acids in the body is that which has been undertaken by Dakin.*It may be taken as pretty well proved that protein matter in thebody yields carbohydrate, quite apart from the glucosamine whichin some proteins is contained as a prosthetic group.Certain amino-acids, of which alanine is the one that has yielded the most positiveresults, are after administration converted into either glycogen inthe liver or sugar in the urine. The substitution of hydroxyl forthe amino-group in alanine will give us lactic acid, and lactic acidis readily formed from sugar, and so it is probable that the oppositechange from lactic acid to sugar may also occur.This, however, isonly one possibility, and certainly the more intimate chemistryof such reactions is still a matter of hypothesis only, and is difficultt o explain. Lang has shown that enzymes are present in the liverwhich remove ammonia from amino-acids, and Dakin considers thatferment activity will also explain the removal of carbon dioxidefrom their carboxyl group, as in the transformation of ornithine intotetramethylenediamine. Now if both ammonia and carbon dioxideare removed from an amino-acid, an alkyl group rich in carbon isleft, which might be further transformed into carbohydrate, or intocarbon dioxide arid water. Dakin selected a method which closelyapproximates a biochemical reaction, namely, Fenton’s method ofoxidation by means of hydrogen peroxide and a trace of acatalyst such as ferrous sulphate ; the amino-acids selected forexperiment were glycine, alanine, and leucine.All of these may berepresented by the formula NH,*CHR*CO,H, where R is either aZeit. physiol. Chenb., 1906, 47, 339 ; Abstr., 1906, ii, 470.Ibid., 376 ; Abstr., 1906, ii, 470.Ned. Klin., 1906, No. 6 ; Abstr., 1906, ii, 874.+I J. Biol. Chem., 1906, 1, 171 ; Abstr., 1906, ii, 105.The same method has been adopted by Battelli and Stern (Compt. rend., 1905,141, 916 ; 142, 175 ; Abstr., 1906, ii, 107, 184) in their investigations of oxidationsin tissues and tissue extracts. The place of the ferrous salt is in the body taken bywhat they term anti-catalase, and this disappears soon after death. Lactic, acetic,and formic acids are decomposed and carbon dioxide evolved.The method does notoxidise urea, and urea is also the chief nitrogenous end-product in the body240 ANNUAL REPORTS ON THE PROGRESS OF CHEMTSTRS.hydrogen atom as in glycine, or a methyl or isobutyl group (as iualanine arid leucine respectively). On oxidation all are readilyresolved a t the ordinary temperature into carbon dioxide, am-monia, and an aldehyde. In the case of glycine, the aldehyde pro-duced is formaldehyde, and this is the substance which is obtainedphotosynthetically in plant life, and is there the undoubted fore-runner of carbohydrate, into which it is transformed by condensa-tion, a process which has been successfully imitated in the laboratoryby Butleroff and Fischer.It was, however, found that the yieldof aldehyde was less in the case of glycine than in that of alanineor leucine; this is because it is partly oxidised into formic andglyoxylic acids. The formation of glyoxylic acid is not without in-terest, as this acid occurs in unripe fruit, and on ripening is con-verted into sugar.I n similar fashion, alanine yields acetaldehyde and acetic acid(but not pyruvic acid, the acid corresponding with glyoxylic acid),whilst leucine yields isovaleraldehyde and isovaleric acid.I think all chemists will agree that this research marks an im-portant advance, and one that should lead investigators onward.It is not until chemists are able t o repeat vital processes, by methodsthat they understand, that they can hope to comprehend what isoccurring in the hidden laboratory of the living cell. Not the leaststriking of the conditions of Dakin’s experiments is that they oc-curred at the ordinary temperature.GZyoqZic Acid.-The possibility that this substance is a productof metabolism is shadowed in Dakin’s work, and is shown to be aprobability in a later paper by the same worker.1 He was not,however, the first in this particular field, for Almagia and his col-leagues Pfeiffer and Inada had previously suggested that it is adecomposition product of uric acid, and found it in the urine,especially of people suffering from gout.I n herbivora fed on hay itis also present, and is derived there from the aromatic substances inthe food. It cannot, however, be said that the test adopted for thedetectioq of glyoxylic acid in urine is a very convincing one.Hopkins and Cole showed that the so-called Adamkiewicz reactionfor proteins depends for its occurrence (1) on the presence of thetryptophan group in the protein, and (2) on the presence of an im-purity (glyoxylic acid) in the glacial acetic acid employed.Eppin-ger3 had the brilliant idea that not only may glyoxylic acid beused as a test for tryptophan, but that tryptophan may also be usedas a test for glyoxylic acid. Subsequent observers, however (for1 J. Biol. Chem., 1906, 1, 271 ; Abstr., 1906, ii, 374.Bcitr. &em. PhysioZ. Path., 1905, 7, 4.59, 4G6, 473 ; Abstr., 1906, ii, 109.Ibid., 1905, 6, 492 ; AbstT., 1905, ii, 543PHYSIO1,OGICAL CHEhlISl'RY.241iustauce, l)akiii,l Schloss2), have pointed out that this does lrotnecessarily follow, and regard the test as untrustworthy, becausetryptophan may give the same coloration with other substancesalso.Schloss has introduced a modification of the Eppinger test, butwhether this is more satisfactory remains to be proved. Eppingerstated that the administration of various substances (alcohol,glycine, glycolic acid, sarcosine, betaine, &c.), led to the appear-ance of the acid in the urine, but this Schloss could not confirm.He only obtained a positive result when allantoin was given, andthis is by no means an unimportant result in view of Almagia'stheory of the relationship of glyoxylic acid to uric acid nietabolism.Schloss further examined the organs of the body, and believes thatglyoxylic acid when formed is destroyed in the body, especially inthe liver and brain.Whether glyoxylic acid is concerned a t all in the Adamkiewiczreaction appears questionable when one considers some results re-cently published by Rosenheim.3 He quite agrees with Hopkins andCole in regarding the reaction as due t o the presence of the trypto-phan (indole) group in the protein molecule.But he obtains whatappears to be an identical reaction both to the naked eye and t othe spectroscope when formaldehyde is added t o a protein solutionin the presence of sulphuric acid containing oxidising agents. Ac-cording to this view the impurity in glacial acetic acid responsiblefor the colour is not glyoxylic acid, but formaldehyde, and thepresence of impurities in the sulphuric acid (for instance, nitrousacid, ferrous salts) is also necessary ; these produce diformaldehyde-peroxide hydrate, and this reagent gives the test in the presenceof protein and pure sulphuric acid.I understand, however, fromDr. Hopkins that he is prepared to defend his original views, andthere we must leave) the question for the present; but until it issettled, the search for glyoxylic acid by means of tryptophan must besuspended.Lactic il cid in Intermediary Metuboli.s?n.-I mentioned lactic acidjust now as a possible intermediary between alanine and sugar in thebody. The whole question of the meaning of lactic acid is notonly fraught with interest, but also surrounded with great difficul-ties. Its close relationship to sugar is undoubted, whether we are con-cerned with the building up or the breaking down of sugar moleculesin metabolism, and yet the idea is gaining ground that the mostimportant variety of lactic acid found in the body (dextrorotatoryor sarco-lactic acid) has a protein origin, by way of such amino-acidsBeitr.ehem. Physiol. Path., 1906, 8, 445 ; Abstr., 1906, ii, 785.VOI,. 111. R' Loe. cit.3 Biocliem. J., 1906, 1, 233 ; Abstr., 1906, ii, 508242 ANNUAL REPORTS ON THE PROGRESS OF‘ CHEMISTRY.as alanine, and its compounds phenylalanine and tyrosine. G.Lusk and A. R. Mandell found that lactic acid disappears. fromboth blood and urine in phosphorus poisoning, when phloridzin glyco-suria is induced.This indicates that lactic acid produced from pro-tein (whether in liver, intestinal wall, o r elsewhere) is first syn-thesised t o sugar within the body before further distribution t o thetissues occurs. I n phosphorus poisoning this is followed by cleavageand a second production of lactic acid. But when diabetes is pre-sent, and when the mammary glands are utilising dextrose to formlactose, then the cells affected become “sugar hungry,” and alsoattract fat in greater quantity than they can burn it, and so fattydegeneration, which is really fatty infiltration, is seen. I n thediabetic organism there is therefore a complete conversion ofd-lactic acid into dextrose, and the same is true partially for i-lacticacid.The difficulties of the lactic acid question have led observers inthe past into curious mistakes ; the convulsions of puerperal eclamp-sia have, for instance, been attributed to the presence of the acidin the blood and cerebrospinal fluid.2 The acid is there, but it isobviously and undoubtedly the consequence and not the cause ofthe convulsions.Ferments.There is nothing very new or very striking to mention in rela-tion to work on enzymes during the last year.It is becoming moreand more certain that these agents act as catalysts in increasing thevelocity of chemical reactions.3 A succinct and very readableaccount of this modern view of ferment action has been writtenby Bayliss, and published in Mi. Murray’s new review, Science Pro-g r e ~ s .~ There are, of course, certain differences between enzymesand the inorganic catalysts (for instance, their destruction by a hightemperature), but, as Bayliss points out, these are all explicable ont,he hypothesis that the former are colloidal substances.I n addition to the papers of Armstrong which have been alreadymentioned, there have been others on what one may term isolatedpoints, such as the velocity of action of t r y p ~ i n , ~ the supposed iden-tity of rennin an’d pepsin,G the decomposition of caseinogen byAmer. J. Physiol., 1906, 16, 129 ; Abstr., 1906, ii, 463.This view is not altogether confined t o the past, but has again been urged byseveral investigators during the present year (Zmeifel, Munch. mcd. Woch., 1906,53, 297 ; Futh and Lockeman, Centr.Gpaek., 1906, 41 ; Abstr., 1906, ii, 472.3 See, for instance, Neilson, Arner. J. Physiol., 1906, 15, 148 ; AbStr., 1906, i,125. Oct., 1906, 281.See also same authoron Anti-trypsin, Biochem. J., 1906, 1, 474, 484 ; Abstr., 190% ii, 780.Hedin, J. Physiol., 1906, 34, 370 ; Abstr., 1906, ii, 780.Sawjaloff, Zeit. physiol, Chem., 1905, 46, 307 ; Abstr., 1906, ii, 98PHYSIOLOGICAL CHEMISTRY. 243trypsin and alkalis,l all of which are interesting in themselves, butdo not lend themselves to a general discussion.In reference to co-ferments, it is apparently becoming establishedthat these are, as hinted in last year’s report, of a simple and stablenature, being, in some cases a t any rate, inorganic in nature. Inthis relation the papers by Delezenne 2 on the activation of pancrea-tic juice by calcium salts, by Harden and Young3 on the alcoholicfermentation in which the presence of phosphates will partly, butcertainly not entirely, explain the favouring action of boiled yeastjuice, and by Loevenhart: in which Magnus’s co-ferment of lipaseis shown to consist of bile salts, should be read.Plimmer’s paper on the adaptation of the pancreas to lactose5does, however, raise a general question.The idea that the organismis able to adapt its secretions t o the calls made upon it originatedfrom the brilliant and suggestive work of Pawloff, and one of themost remarkable of these adjustments was described by Weinlandand later by Bainbridge; they stated that in animals which receivedno milk in their food, no lactase was secreted by the pancreas; butthe administration of milk or lactose to the animals educated the pan-creas to secrete the ferment necessaryfor the hydrolytic cleavage ofmilk sugar.Plimmer has now shown that this result was due to fal-lacious methods of experiment and analysis, and that this supposedadaptation does not really occur. This has certainly not killed thenotion of adaptation,6 but it has removed from it a very importantpillar of support, and this naturally leads one t o hesitate beforeaccepting other proofs, and to demand that the experiments be re-peated with more rigorous control^.^Cleavage of Peptides b y Enzymes.-This is also another importantgeneral question, although it is early days yet to attempt anygeneralisation.The peptides are numerous, and enzymes arenumerous? and t o work out all the possible combinations and permu-tations will take time; and this is the Herculean task Fischer, Abder-halden, and their colleagues * have started. Some of the peptideshyliss and Plimmer (J. Physiol., 1906, 33, 439 ; Abstr., 1906, i, 325.2 Compt. rtmd., 1905, 141, 751, 914 ; Abstr., 1906, ii, 99, 100.3 Proc. Roy. Soc., 1906, 77, 3, 405 ; Abstr., 1906, i, 470.4 Proc. Anzer. Physiol. Xoc., 1905, x w i i ; Amer. J. Physiol., 15 ; Abstr., 1906,5 J. Physiol., 1906, 34, 93 ; Abstr., 1906, ii, 239.6 There are, for instance, papers still being published in relation to i t ; see‘( Adaptation of tlie Salivary Secretion,” by Neilson and Terry (Amer.J. Physiol.,1906, 15, 406 ; Abstr., 1906, ii, 238).7 A more recent paper by Plimmer (J. Physiol., 1906, 35, 20) has already adducedevidence that other cases of supposed adaptation have no foundation in fact.8 Some of the most important papers in the series are as follow: Zeit. physiol.Chem., 1905, 46, 5 2 ; 1906, 47, 346, 359, 391, 466 (Abstr., 1906, ii, 99, 462, 464).i, 328.R 244 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.undergo cleavage, some do not, arid others are broken up only bycertain enzymes. For instance, glycyl-Z-tyrosine is readily decom-posed into its constituents by trypsin, but not by pepsin-hydrochloricacid; such an observation furnishes us with a distinguishing char-acter of these two enzymes which has for so long been lacking.Glycylglycine is not split by pancreatic juice, but it is by liverextract.Such an observation started Abderhalden on the track ofexamining the action of various tissue extracts, and there is no doubtthat a knowleldge of the part played by these tissue enzymes willteach us a great deal about intermediary metabolism. Enzymeshave in many cases been known to exhibit a " reversible action," andso it is quite possible that the same ferments which split peptidesmay also, when acting the other way round, contribute t o the syn-thesis of proteins in the tissue cells. No evidence of reversibleaction has, however, been forthcoming in the experiments hithertoperformed in. uitro.1Studies of this nature, and studies on autolysis, have establishedthe importance of the tissue enzymes; we now know that fermentswhich produce hydrolysis are not confined to the interior of thealimentary canal, but that most of the body cells are provided withferments of most diverse kinds, which assist them either in utilisingthe nutrient materials brought to them by the blood stream, or inbreaking them down previous to expelling them as waste substances.Claude Bernard, when he discovered the ferment which enablesthe liver cells to transform glycogen into sugar, little foresaw thatthis was the first of a long series which were t o be discovered manyyears later.Among such later discoveries we may mention tissueerepsin and arginase.But the best instance of all is seen in the formation of uric acidfrom nuclein; in this case we have t o deal with numerous fermentsacting in succession.Thanks t o Walter Jones in America andSchittenhelm 2 in Germany, our knowledge on this question is prettycomplete. The two observers have indulged in a certain amount ofpolemics, but those who are outside the controversy will rejoice that,after all, on the main questions involved there is agreement. Thefirst ferment to come into play is mudease, and this liberates thenuclein bases. This ferment is found in pancreatic juice, but it isnot identical with trypsin; in fact, it is destroyed by tryptic action(Sachs 3) ; it is, however, also found in the extracts of many tissues,and so the work started in the intestine is finished by the tissue cells.Abderhalden and Rona (ZeiLphysioZ.Chern., 1906,49, 31 ;'Abstr., 1906, ii, 873).Jones and Austrian (Zeit.physioZ. Chem., 1906, 48, 110 ; Ah&., 1906, ii, 561) ;Schittenhelm and Abderhalden (ibid., 47, 452 ; Abstr., 1906, ii, 465). For previouspaper, see last year's Report.Zeit. physiol. Chem., 1905, 46, 337 ; Abslr., 1906, i, 126PHYSIOLOGICAL CHEMISTRY. 245The next ferments which act remove the amino-group from thepurine bases that contain it; thus adenine (C,H,N,*NH,) is con-verted by ndenase into h-ypoxanthine (C,H,ON,) and guanine(C,H,ON,*NH,) is converted by gmnase into xanthine (C,H,O,N,).Finally, oxydases step in and oxidise hypoxanthine into xanthine,and xanthine into uric acid (C5H403N4). By examining extracts ofvarious organs, the distribution of these numerous ferments is foundto vary somewhat in different animals, although in general thespleen and the liver are the organs where they are most abundant.But the examination of such extracts has shown in addition thatthe long list is not yet complete, for some extracts in part breakup the uric acid which has been formed into simpler substances,1and the ferment which destroys uric acid is called the uricolyticferment.2 We therefore learn that the uric acid discharged inthe urine is only the balance left over when the amount destroyedis deducted hom the amount originally formed.In other words,the body possesses t o some extent the power of protecting itselffrom an excessive formation of uric acid, and so from the evilswhich would result from an accumulation of this substance.The Secretion of Urine.Bowman was the first t o put forward the hypothesis that the for-mation of urine is a double process; the glomeruli consist of bloodvessels in which there is high pressure, and consequently they havebeen looked on as a filtering apparatus where water and certainsoluble salts escape. The convoluted tubules with their secretoryepithelium are the parts of the apparatus where urea and other or-ganic substances are added to the glomerular flow.The secretingcells are able t o pick out the urea, mainly formed in the liver, fromthe blood, and transfer it to the urine.Ludwig, on the other hand, considered that practically all theurinary constituents found an exit from the blood a t the glomeruli,and that the function of the tubules was t o reabsorb some of thewater and so increase the concentration of the urine.This view hasbeen supported by the recent work of Cushny, who has put forwardevidence that reabsorption of water, and t o a certain .extent ofsome salts, occurs in the tubules. The whole tendency of modernresearch, however, apart from Cushny’s work, has been t o confirmthe original statements of Bowman, and to prove the tubules to haveas their principal function secretion and not absorption.1 See also the papers by Alinagia and his colleagues already quoted.3 The fact that uric acid is destroyed is no new discovery, however. See, forinstance, H. Wiener (Arch. exp. Path. Pharm., 1899, 42, 374 ; Absts.., 1090,ii, 153)246 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The work of Brodie and Cullis1 is a very important piece ofresearch from this point of view.They found, in a dog in whichdiuresis was produced by sodium sulphate, that the volume of urinesecreted by one kidney which was working against a small ureterpressure was greater than that formed by the other kidney whicheerved as a control; the volume of sulphate secreted on the ob-structed side was also usually in excess. A saline diuretic excitesthe cells to greater secretory activity, and does not work solely bycausing changes in the blood and in the circulation. Nevertheless,it was necessary in such experiments to exclude any artificialchanges in the blood flow through the kidney, and this was doneby making the ureter pressure sufficiently small.I f phloridzin wasemployed, the volume both of the urine and the sugar was greateron the obstructed side. Such results negative Ludwig’s view ofkidney action, for an increased pressure in the ureter. would promoteabsorption if Ludwig’s theory is true; they indicate that the glo-meruli will excrete more watler and probably more salt, and that thetubules excrete more salt when excited by a small ureter pressure.Heidenhain’s old experiment with indigo, in which he showedthat the tubules and not the glomeruli are the places where theexcretion of this foreign substance occurs, has recently been repeatedby Basler.2 This observer further introduced the indigo into thekidney calyces, but could not find that i t was reabsorbed by theliving cells of the tubules, although some ultimately diffuses back-wards into the lumen of tho tubules. But if the same experimentwas performed with sodium ferrocyanide, this salt was shortly after-wards excreted by the other kidney.This certainly shows that ab-sorption of the salt had occurred, but it does not prove that thecells of the tubules had been instrumental in the absorption; itrather appears that the salt had simply diffused into the lymphvessels or blood vessels in the neighbourhood of the injection.The mammalian kidney presents much greater difficulties to theexperimenter than the kidney of the frog; and Nussbaum, who fol-lowed in Bowman’s footsteps, utilised the fact that the glomeruli inthe latter animal are supplied with blood by the renal artery and thetubules by a different vessel, namely, the renal-portal vein, in his clas-sical experiments by which he sought to unravel the part played bythe two mechanisms. Nussbaum’s anatomical facts are undoubtedlytrue, and there is no anastomosis between the two sets of bloodvessels;if all the branches of the renal artery are tied, the glomeruli are ren-dered absolutely bloodless ; Bainbridge and Beddard 3 showed, how-l J.Physiol., 1906, 34, 224 ; Abstr., 1906, ii, 468.3 Proc. Physlsiol. Soc., 1906, ix, J. PhysioE., 34; Abstr., 1906, ii, 469 ; BiochesaPfluger’s Archiv, 1906, 112, 203 ; Abstr., 1906, ii, 468.J., 1906, 1, 255 ; Absti.., 1906, ii, 563PHYSIOLOGICAL CHEMISTRY.247ever, that undeF these conditions, although the tubules are stillreceiving blood, the kidney absolutely refuses to work a t all; forthe blood they receive is venous blood, and the loss of an arterialsupply asphyxiates the kidney and leads to death and desquamationof the renal epithelium. This may be obviated by placing the frogin nearly pure oxygen a t atmospheric pressure, and a secretion ofurine follows the injection of urea, dextrose, phloridzin, or disodiumhydrogen phosphate.Experiments on artificial perfusion lead also to similar results (MissCullis l). By quite simple operations, an arterial perfusion (by wayof the renal artery to glomeruli), a venous perfusion (by way of renalportal vein to tubules), or both (that is, a total perfusion), may be ob-tained; and the necessary oxygen supply is kept up by means ofoxygenated saline solution (Locke's fluid).Various diuretics wereadded to the perfusing fluid, and their effects noted. Phloridzinwas found to excite the tubule cells directly; they form dextrose anddischarge it into the urine. Caffeine also excites the same cells,although i t also probably has a slight similar action on the glomerularepithelium. With sodium sulphate, no flow of urine occurs unlessthe circulation through the glomeruli is maintained, and other salinediuretics act in the same way. Dextrose acts mainly on the glom-eruli, but to a small extent on the tubules. Both glomeruli andtubules are concerned in the elimination of urea, but there were somediiliculties in determining the relative importance of the two, forstrong solutions of urea kill the cells. Again, as in the dog, analysisof the urine showed no evidence of reabsorption in the tubules.Such experiments undoubtedly prove the power of secretion whichthe cells of the tubules possess.They do more than this; they showthat the old idea that the glomerular apparatus is a passive filter isincorrect, but that the cells that cover it, thin though they are, arenevertheless secretory also. At the meet'ing of the British Associa-tion in Toronto, Brodie advanced the view that the high blood pres-sure in the glomeruli is not to promote filtration a t all, but to enablethe glomerular tuft a t the commencement of each renal tube to actas a sort of force pump t o assist in driving the urine to its destination.Basler has also called attention to the high resistance the glomerularoutflow has to overcome in the narrower portions of the tubule, as, forinstance, in the loop of Henle.Whether this new idea will ulti-mately prevail it is a t present impossible to prophesy. Bainbridgeand Beddard, who concur in regarding the glomerular epitheliumas secretory, also suggest the presence of secretory nerves; nerveendings have been found by Berkeley in the renal epithelium, andit is difficult to explain diuresis following injury to the centralnervous system without assuming that these act as secretory nerves.J. Physid., 1906, 34, 250 ; Abstv., 1906, ii, 468248 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.An interesting outcome of such studies is a calculation of the workwhich the kidney does.The kidney cannot be doing more workthan its metabolism accounts for. If we suppose the kidney liveson its protein (and the figures would not be very different if wesupposed it lives on carbohydrate), we start with the following con-stants : -1 C.C. of oxygen oxidises 1 milligram of protein, and formswater, carbon dioxide, and urea (Barcroft and Brodie 1) ; in doingso it gives out 4 large calories, to adGpt Rubner's figure f o r the physio-logical heat value of albumin. I n a certain experiment the oxygenused by the kidney was 4 C.C. per minute; this was equivalent to 16calories, or to 680,000 gram-centimetres of work, and the energytransformed from potential to kinetic cannot have been less thanthat.What evidence is there of mechanical work as an offset againstthis? One way in which the work manifests itself is in the concen-tration of the urine. The urine in regard to its various constituentsis many times more concentrated than the fluid of the blood, andfrom freezing-point determinations it was found that 14,700 gram-centimetres of work were done in this way in the example just taken.No doubt if the calculation took into account each salt separately, ahigher figure than 14,700 would have been obtained, but even thenmuch of the kidney energy is left unaccounted for; we can onlysuppose that the transference of water itself a t a rapid rate throughprotoplasm is on occasion a process which involves the active meta-bolism of the cells.Micro-ch emistry.The number of workers a t this instructive and important aspect ofbiological work is lamentably small.I n addition to the paper byE. Mayr already quoted on the influence of salts on the staining andfixation of nerve-tissues, there is only one other of importancethat I can find in the year's output. This also deals with nerve-cellsand fibres, with special reference t o the distribution of chlorides inthem (Macallum and Menten ". Macallum has shown previouslythat the well-known reduction staining with silver nitrate, so muchused in histology, is due to the presence of chlorides. The transversestriations produced a t the nodes of Ranvier in nerve-fibres, andtermed the lines of Frommann, can be obtained at any portion ofthe axis cylinder, provided means are taken to allow the reagent toget a t it. These lines do not indicate, however, a pre-existing dis-tribution of 'the chlorides in alternating layers.The same appear-ance can be reproduced in capillary tubes containing egg-white, orgelatin impregnated with potassium dichromate (Boehm, Liesegang).Ostwald explains this by supposing that, when the critical concen-J. Yhysiol., 1905, 33, 52.€'roc. Roy. A'osoc., 1906, 77, B, 165 ; Abslr., 1906, ii, 182PHYSIOLOGICAL CHEMISTKY. 249tration in the advancing solution is reached, precipitation beginsand is continued until a stria is formed. This brings the solutionback to the metastable condition; then another development of thelabile condition obtains, and thus a new stria after an interstriatezone is formed.As the silver salt becomes more and more dilute,critical concentration is obtained later and later, and so new stria3are separated by interstriate zones of increasing width.The cytoplasm of the nerve cell shows the same appearances, butless intensely; this may be due to difficulty of penetration, but i tis held that probably the cell-body is poorer in chlorides than theaxon. The nucleus is destitute of chlorides.The mixture of electrolytes and colloids in the nerve-fibre wouldnot permit the ions carrying the electrical charge to travel unim-peded, and the change of potential transmitted would travel withdiminished velocity.This would bring into line the nerve impulseand the action current of nerve. It is freely admitted that cautionmust be exercised at present in drawing physiological conclusionsfrom physical data, but the following facts are very suggestive : -(1) the presence of electrolytes (chloride or chlorides) in a concen-trated degree and uniform in distribution; (2) the maintenance ofthis concentration through the impermeability of the sheaths of thefibres, and (3) the high conductivity of the axon, and the occurrenceof electrical phenomena when it is injured.Such speculations should be compared with those set forth byMacdonald in papers already referred to.Receptive Substances.I started this report with the laudable intention of avoiding, asfar as possible, speculative questions, but I find I have again landedmyself in the last section in another of those interesting regionswhere physical chemists and physiologists can meet and argue.Inthe present state of physiology it is, in fact, impossible to avoidhypothetical matters, and it is quite impossible also to conclude areport of this kind without a reference t o Langley’s recent sugges-tions on “ receptive substances.” The idea seems t o form an under-lying basis of a good deal of the work that has recently come outof Cambridge,l and it has finally found expression in the Croonianlecture which Prof. Laagley delivered before the Royal Society.2We may best approach it, as Langley himself does, by a definiteexample. Nicotine causes prolonged contraction in certain muscles1 See, for instance, H.K, Anderson on “The Action of Alkaloids on the Iris”( J . Physiol., 1905, 33, 414 ; Abstr., 1906, ii, 104).2 Proc. Roy. SOC., 1906, 78, B, 170-194. The question is also treated in J.Physiol., 1905, 33, 374 ; Bbstr., 1906, ii, 111250 BSXUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of the bird even after their nerves have been cut, or after paralysishas been caused by curare. The nicotine contraction is lessened bya sufficient dose of curare, the two poisons being antagonistic, butnicotine is the more powerful. Degeneration of the motor nervesleaves these effects unaltered, but there is increased responsivenessto nicotine, and the action of curare is less marked. Under theseconditions, the axon endings are destroyed, and so the drugs mustact on the muscle itself; but as the muscles respond to direct stimu-lation, the poisons cannot be acting directly on the contractilesubstance, but on other substances in the muscle, which may betermed ‘‘ receptive substances.” This deduction may be applied t oother cases, and the majority of poisons ordinarily supposed to acton nerve-endings probably act on receptive substances in the cellsthe nerve-endings are distributed to. Adrenaline falls into thiscategory ; and secretin, iodothyrin, and other internal secretionsmay also act in the same sort of way, although the cells tiiey stimu-late may have no necessary nerve supply.These and many other speculations arising out of the generalidea are propounded, but the original papers must be consultedfor these.It will be sufficient for our purpose merely t o state whatthe general hypothesis is.It is postulated that in all cell-protoplasm two constituents atleast are present: (1) a chief Substance concerned with cell func-tion, and (2) receptive substances which may be acted on by chemicalmaterials, or in certain cases by nervous stimuli. The receptivesubstance affects, or can aEect, the metabolism of the chief sub-stance. A cell, for instance, can make motor or inhibitory recep-tive substances, or both, and the effect of a nerve impulse will thendepend on the proportion of the two kinds of receptive substancewhich is affected by the impulse.It is quite impossible to criticise such a theory a t present, forcriticism, like the main theory, must be supported by experiment.All one can say is that the theory is an exceedingly attractiveone, and one which does explain some of our present difficulties.Previous to the appearance of this new idea, physiologists wereagreed that there are only two possible ways in which a nerveimpulse can fire off such a structure as a muscular fibre, with whichits ending is in contact.One of these ways is an electrical one, theother a chemical one. The electrical theory is known as the ‘‘ dis-charge hypothesis,” and, put in the briefest possible way, it assumesthat the stimulus to muscular action is the current of action in thenerve terminal. Electro-physiologists have been fairly successful inexplaining away most of the objections which have been raisedagainst the “ discharge-hypothesis,” but they have never, t o mymind, succeeded in solving what is the greatest difficulty of all, anPHYSIOLOGICAL CHEMISTRY.251that is the mystery of inhibition. An action current, feeble thoughit is, is still a conceivable agent in rendering another tissue active.It is most difficult to understand how it can succeed in renderinganother tissue inactive, as, for instance, the vagus does the heart.An attempt has been made to explain the phenomenon of inhibi-tion by assuming differences in shape in the nerve-endings; in theordinary motor nerve terminal it has been supposed that the effecta t the entrance of the fibre, a spot which plays the part of thecathode of the terminal, is most concentrated, because the enteringpoint is a small one, whereas the anode consists of a number ofwidely-distributed points in the final branchings of the axon, andso the anelectrotonic or depressing effect is more diffused, and there-fore not so effective.Oni the other hand, the end orgm of aninhibitory fibre is assumed to be pear-shaped; the base of thepear is a t the entering of the fibre; the end organ then narrows offto a stalk, the end of which is the anode; the anode being thena smaller point than the wide cathode, anelectrotonic effects aremore concentrated, and so more effective; in fact, sufficiently so toovercome any stimulating effect the cathode would have. There is,however, very little histological evidence, and certainly not convinc-ing evidence, that inhibitory nerve-endings have such a shape as thetheory demands.Langley’s new hypothesis appears to be the first workable onein favour of the view that a nerve acts as a stimulus by producingchemical changes, and it is certainly easier to understand oppositechemical changes, or the reversal of a chemical change, than toimagine opposite electrical effects produced by differences in theshape of the nerve-ending.If, however, a muscle is rendered activeby the production of a chemical material that plays the part of astimulus, and if it is rendered inactive by the production of chemicalchanges in the opposite direction, we really only throw the maindifficulty further back; for we have still to ask how is it that thenervous impulses produce these chemical effects on the receptivesubstance or substances? Even if the presence and importance ofthese receptive substances, or intermediaries, between nerve andmusele be admitted, it may be still necessary to call to our assist-ance the “ discharge hypothesis,” or some variation of it, to explainhow the nerve affects the intermediary material.W.E. Dixon1 has already brought forward evidence that chemicalsubstances are produced in the heart when it is inhibited, and that1 Commnnicxtion to the British Association, Toronto meeting, 1906. Quiteanother aspect of the clicmicnl relationships of nervous action has been advanced byF. H. Scott (Brain, 1905, p. 506 ; Abstr., 1906, ii, 239).He considers that nerves:%re able to control changes in proteins, because of a proteolytic enzyme produced innerve-cells252 ANNUAL REPORTS ON THE PROGRESS OF CHEXISTRY.these substances can be dissolved out of the heart by alcohol, andcan then b’e used to produce inhibition in another heart. Thesubstance or substances cannot be extracted from a normally beatingheart; but we have no information as yet in regard to their chemicalcomposition. They appear, however, not to consist of potassiumsalts, to which Howell attributes such an important r6Ze in cardiacinhibition.Cuncer.I shall conclude my report by again referring to the importantquestion which I took up as the concluding section to last year’sreport. I then expressed the belief that chemistry will assistin the solution of the many problems that surround the pathologyof cancer.For instance, the important observation that the gastrichydrochloric acid is scanty or absent in this disease, even whenno actual caiicer is present in the stomach itself, cannot be meaning-less.z Investigations of the various proteins (nucleo-proteins, &c.)obtained from the tumours have not led to much a t present: butthese substances will have to be still further examined.Perhaps I was a little too positive when I stated that the parasitictheory of cancer was dead; I ought to have said that all the para-sites, animal and vegetable, held responsible by different observersfor the disease have hitherto turned out disappointments.It is difficult t o transmit the disease t o animals, and this limitsthe field of observation, but there is a transmissible disease of micewhich most pathologists agree is a form of cancer, and from thestudy of which there are great expectations. This disease was firstdescribed by Morau 4 in 1891, and subsequently by Jensen, of Copen-hagen, in 1903.It is a disease of the mammary gland; histologic-’ ally it closely resembles other cancers; it is followed by metastases(secondary tumours in other parts of the body), and it is malignant;that is t o say, it kills the mouse. Whether it is absolutely the samedisease as human carcinoma is another question, and a t a meeting1 Amer. J. Physiol., 1906, 15, 280 ; Abstr., 1906, ii, 179.2 Full papers on this point by E.Moore and his colleagues will be found i nEiochem, J., 1906, 1, 274, 297 ; Abstr., 1906, ii, 565. See also K. Sick (Arch. kliib.Ned., 1906, 86, 371 ; Abstr., 1906, ii, 565 ; Palmer, Biochein. J., 1906, 1, 398 ;Abstr., 1906, ii, 786).3 See, for instance, Neuberg, Zeit. Krebsforsch., 2, 171 ; Abstr., 1906, ii, 875.4 Conzpt. rend. A’oc. Eiol., 1891, pp. 289, 721, 801. Moran’s work came a t a timebefore cancer iesearch was in vogue ; helie5 the disease is generally known asJensen’s tumour. Jensen showed that in inoculated mice the new formation is acontinuation of the growth of the cells introduced by inoculation. The relativeimportance of the work of Morau and Jensen has been the subject of recent corre-spondence in the Lancet (Nov.and Dec., 1906), and doubt has been expressedwhether the two investigators were dealing with the same diseasePHYSIOLOGICAL CHEMISTRY. 253of the Pathological Society in Loudou a few weeks ago the experi-mental and pathological work on mice was spoken of as futile.This, of course, is the view of an extremist, and the correct attitudeshould be a more hopeful one. Curiously enough, however, in thesemice there is no fall in the secretion of hydrochloric acid in thestomach, but the reverse,l so it does appear there are grounds forhesitation in accepting the disease as identical with that in thehuman subject.A vast amount of work has been performed in relation to theJensen tumour. It is transmissible by inoculation from mouse t omouse, and already thousands of mice have borne their part in theinvestigation.I propose, however, only to deal here with the workthat has issued from the New York Cancer Laboratory a t Buffalo,because there a distinctly chemical bias has pervaded it.2 Chemistsas well as biologists have now invaded the territory of the patholo-gists, and Clowes with his colleagues have kept accurate records ofthe many thousands of mice they have had under observation.They have found that the disease may not only be given to theanimals by inoculation or injection of material from other mice, butalso that there is further distinct evidence of infectiousness in otherways. For instance, mice transferred to cages which had not beencleaned, but which had held infected animals long previously, de-veloped the disease. Such observations place this form of carcinomaon all fours with other infectious diseases, and lead one naturallyt o think that the active agent must be a living organism.Whatthe actual agent is, is still unknown, and it is necessary to exerciseextreme caution in drawing conclusions on this point. Some ofthe micro-organisms described by others are merely due to accidentalcontamination, and other supposed organisms are really artifacts.Calkins and Clowes draw attention to artifacts both in the nucleiand cytoplasm of the cancer cells, even in material fixed by Zenker’smethod (alcohol and iodine) ; the curious inclusions which theydescribe are artificial, but are found usually in the cells which areundergoing degenerative necrosis, and the method, therefore, is inone sense a valuable one in distinguishing the active cells fromthose undergoing the process of death- which is probably associatedwith a kind of fatty degeneration.Copemnn and Hake, La?zcet, 1906, ii, 1276 ; Abstr., 1906, ii, 875.The principal papers are as follows : H.R. Gaylord and G. H. A. Clomes, Mecl.News, Jan. 14, 1905 ; Xurgery, Gynmcology and Obstetrics, 1906, 2, 633 ; G. H. A.Clowes, Johns Hopkins Hos2)ttal Bulletin, 1905, 16, No. 169 ; G . H. A . Clowes andF. W. Baeslack, Med. News, Nov. 16, 1905; J. Exp. Med., 1906, 481; G. H. A.Clowes and W. E. Frisbie, Amer. J. Physiol., 1905, 14, 173 ; G. N. Calkins andG . H. A. Clomes, J. Infectious Diseases: 1905, 2, 555 ; G.H. A. Clowes, Brit. Med.J., 1906, ii, 1548 ; H. R. Gaylord, ibid., 15552.54 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The tumours, in fact, may roughly he divided into two varieties :(1) those which are growing rapidly, characterised by a high per-centage of potassium, with little or no calcium, and (2) those whichare old, slow-growing, and necrotic, characterised by a high per-centage of calcium, with little or no potassium (Clowes and Frisbie).The second class of tumours may not only be slow growing; theymay even diminish in size, and this may culminate in their disap-pearance, and the animals recover perfectly without any treatmenta t all. Bashford stated he had only seen one case of recovery in3,000 mice,l but in the experiments of Gaylord and Clowes spon-taneous recovery occurred in 23 per cent. of the cases.The retro-gression of the growth is attributed to the development of immuneforces, as in other infectious maladies, and the observation led theauthors to search for cases of spontaneous recovery in humancancer. They found fourteen apparently authentic cases in pre-vious records, but hearsay evidence of this nature is usually re-garded with suspicion, not only by lawyers, but by scientific workerstoo. I doubt if there are many medical men who would not regardthe occurrence of cancer in a human being as equivalent t o a sen-tence of death, and there are certainly none who would advise theirpatients t o trust to spontaneous cure instead of submitting them-selves t o that surgical interference which alone can avert the finaldisaster.The high percentage of spontaneous recovery in mice can bestill further increased by treatment on the lines of serum therapeu-tics. The mice which recover possess an active immunity againstfurther inoculation, and if cancer material from the Jensen tumouris mixed with the serum of the recovered mice, and then injectedinto fresh animals, quite a large percentage of the latter escapethe bad effects of the injections. Injection of the serum leads alsot o more frequent and more rapid recovery.These and similar statements require confirmation, but suchresults certainly make one feel there is hope in serum treat-ment in human carcinoma, and should still further stimulate re-search in that direction. This hopefulness, however, depends on theassumption that human carcinoma and mouse carcinoma are iden-tical or a t least similar diseases. We have already seen groundsfor doubting the identity if in one there is a rise and in the otherdisease a fall in the hydrochloric acid secreted by the stomach, forthis is an index of an altered condition in the ions of the blood.Subsequently he withdrewthis statement, as in later work (Brit. Med. J., July, 1906) he found spontaneousrecoveries i n large numbers, in some series as high as 60 per cent. Immunitydeveloped in mice .with the disease was also found by Ehrlich (Experime?ttelZeCarzinomstzcdien, April, 1906).1 Report of Imperial Cancer Research Fund, 1905PHYSIOLOGICAL CHEMISTRY. 255The relative non-malignancy of the mouse tumour is an additionalseason for making one hesitate in regarding the two diseases as thesame.Be that as it may, and only the future can decide the questicn,the results obtained by Clowes and others are important and sug-gestive; I will only add one more detail of this work, and so bringthis report.to a close.Clowes andBaeslack found that the incubation of the mouse-cancer material before it was injected into other animals altered-itsvirulence. Some of their material was, comparatively speaking, in-active; that is t o say, a large percentage of the mice injected did not“take.” I f this inactive material was kept in the incubator forsome time previous t o injection, its virulence rose, and the per-centage of affected mice increased. This, of course, is analogousto what one finds in most other infective substances.I n other cases the material was virulent a t the ordinary tempera-ture, but the virulence was lessened after incubation a t body tem-perature; this was the material obtained from necrotic tumours witha high calcium percentage. I n order to explain these results it isnecessary t o assume the existence of a toxin. The toxin acts as achemical stimulus to cell-proliferation, and its action is acceleratedby elevation of temperature; hence, comparatively inactive materialis rendered more virulent by the employment of the incubator. Butif the toxin is already abundant, it is quite conceivable that theraising of the temperature will lead, not to multiplication, but t odestruction of the cells, especially in tumours where necrotic changeshave already been initiated by other means. This autolysis willnaturally reduce the virulence of the tumour material.I n order to explain the toxin, it is necessary t o assume theexistence of some agent which will produce it, presumably a livingorganism, but on that final point we have a t present no light.W. D. HALLIBURTON