AGRICULTURAL CHEMISTRY AND VEGETABLEPHYSIOLOGY.MUCH steady progress has to be reported, although no develop-ment of outstanding importance has occurred.The outlook for the future is in some directions rather uncer-tain. The Woburn Fruit Farm, long carried on a t the expenseof the Duke of Bedford, and made famous by the importantinvestigations of the late Spencer U. Pickering, will be closed:before this Report appears; and a t the moment of writing thereis the possibility that the Woburn Experimental Station of theRoyal Agricultural Society may be dosed in 1921, although somehope still remains that this misfortune may be mitigated, or evenaverted. It seems probable that the research in agriculturalscience done by Germany and Austria will be less,in future thanit was before the War.As against that, however, the Ministryof Agriculture in this country has produced an admirable scheme,whereby the research institutes can attract the ablest of theyounger men and women from the universities, and it may safelybe said that the institutes were never before as well staffed as theyare now. Both in amount and quality, the work in hand at thevarious centres of agricultural research in this aountry is full ofpromise for the future. Fortunately, also, in spite of the central-isation which is being forced by inexorable circumstances, therestill remain independent outside critics who can save the workersa t the institutes from the dangers of futility.Soil.It seems possible that the nature of the black organic matterin the soil, commonly known as ‘‘ humus,” will soon be understood.Humus is formed from cellulose in the soil; no great amountseems t o be obtained from the protein in plant residues.Maillardshowed some years ago that a substanoe resembling humus is pro-duced when sugar is heated either with mineral or amino-acids ;in the latter case, the “humus” contains nitrogen, as in soil.17176 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The reaction has been further investigated by V. A. Beckley inthe Rothamsted laboratories; 1 setting out from an observation byFenton, he showed that sugars, on treatment with acids, give riseto hydroxymethylfurfuraldehyde, which readily condenses to forma substance closely resembling humus. He also found indicationsof the presence of hydroxymethylfurfuraldehyde in a dunged soiland in rotting straw in which humus was being produced.Hesuggests, therefore, that the formation of humus in soil proceedsin two stages:Carbohydrate (cellulose, etc.) + aniino-aoid =hydroxymethylfurfuraldehyde,Hydroxymethylfurfuraldehyde + amino-acid =humus + furfuraldehyde + CO, by condensation.An alternative view is put forward that humus is derived fromthe oxidation of quinones.2The humus has acid properties, which, however, are very difficultto measure. An interesting series of papers has been published3by S. Ode'n, of Upsala, one of the most ingenious of present-dayworkers on this difficult subject. He shows that selective absorp-tion, once invoked to account for the acidity, can really play buta very minor part, since treatment of washed peat with potassiumchloride solution gives no hydrochloria acid, but only non-volatileacids. Nor did iron or aluminium occur in the solution.Humicacid is a true acid ; 4 it appeared, however, from the high PR valueof peat extracts that other organic acids were present as well. Amethod is described for obtaining neutralisation curves which willprobably prove distinctly helpful to investigators.It is wellknown that large quantities of lime-one or two tons per aore-are necessary in order t o allow of the growth of agricultural cropson peat soils; whilst on normal soils much smaller quantities suffice.The usual explanation is that peat contains some harmful sub-stance put out of action by lime.Od6n shows that humic acidis so insoluble that it can hardly do much harm to vegetation; healso controverts Baumann and Gully's view that injury arises byabsorptive decomposition of nutritive salts with liberation of acid.Further, he demonstrates by the old van Bemmelen method thatlime effects no improvement in the fundamental water relation-He further discusses the effect of lime on peat.5J . Agric. Sci., 1930, 11, 69.W. Eller and K. Koch, Ber., 1920, 53, [B], 1469; A., i, 733.Int. Mitt. Bodenk., 1920, 9, 361; he has also published EL monographdealing with the whole question of humus : Roll. Chem. BeiheJte, 1929, 10,75. * For further confirmation, see F. Fuchs, Chem. Zeit., 1920, 441, 651 ; A.,i, 696.Int. Mitt. Bodenk., 1920,9, 376AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 177ships of peat. He concludes that humio acid is not itself harmfult o plants, but, on the other hand, the caloium humate formedwhen lime is added t o peat is distinctly beneficial, probably byacting as a “ buffer ” in regulating the hydrogen-ion concentrationof the soil. It would react with harmful acids, forming harmlesscalcium salts and insoluble, harmless humic acid, thus maintainingthe soil reaction suitable for plants and micro-organisms.He also describes a oolorimetric method for estimating theamount of humic acid in soil.6 The problem is complicated bythe fact that two intensely dark-coloured substances occur, namely,humic acid and the so-called hymatomelanic acid, in addition t othe faintly coloured acids formerly known as crenio and apocrenicacids, but named “fulvic” by OdBn.7As separation of the two dark-coloured acids is not easy, adetailed examination mas made of the absorption spectra of theirsodium salts as well as of that of Merck’s “acidum huminicum”;from the curves and data thus obtained the details of the methodare worked out.An aqueous extract of peat undergoes considerable changes onkeeping, which have been examined in some detail.8The organia phosphorus compounds of the soil have been studiedin Ohi0.9 About one-third of the total phosphorus in the surfacesoil and one-fifth of that in the subsoil is found t o be in this form,and this organic phosphorus is related both to the “humus solublein ammonia,” of which it forms about 1 per cent., and to the totalnitrogen, being one-tenth the amount of the latter.There was noevidence that the organic phosphorus compounds have much directnutrient value to plants, although they apparently undergodecomposition, since the amount in virgin soil is considerably abovethat in cultivated soil containing approximately the same quantityof total phosphorus.The black organic matter insoluble in alkalis is known as“ humin ” ; a similar-looking insoluble product is obtained by theinteraction of amino-aoids and tryptophan, tyrosine and formaldehyde.10Soil Acidity.-Much work continues to be done in America onIS Int. Mitt. Bodenk., 1920,9, 391.7 The multiplication of definite names for indefinite soil acids is confusing :it would be better to adopt the biological plan, and speak of ‘ A,’ ‘B,’ ‘(7,’etc., terms which can easily be discarded when more precise definition ispossible.H. Puchner, Kolloid Zeitsch., 1919, 25, 196 ; 1920,26, 159 ; A., i, 274,468.C.J. Schollenberger, Soil Sci., 1920, 10, 127.lo R. A. Gortner and G. E. Holm, J . Amer. Chem. SOC., 1920, 42, 632, 821 ;A., i, 400, 460178 ANNUAL REPORTS ON THE PROGRESS OR' OHBMISTRY.soil acidity. Four explanations have been offered of the powerof soil to turn blue litmus red: selective adsorption (Cameron),the presence of organic acids (Sprengel), of acid silicates (Hopkins,Loew), of easily hydrolysable iron or aluminium salts which arisewhen supplies of basic caloium and magnesium compounds arelow 11 (Abbott, Conner and Smaller, Daikuhara).The existence of a definite hydrogen-ion concentration in acidsoils shows the presence of definite acids, without, however, givingmuch information as to their nature.f2Aluminium nitrate and sulphate are both toxic to plants,especially clover, when applied in amounts equivalent to the acidityof the soil.Aluminium oxide and phosphate, on the other hand,had no effect.13 It was further found that washing soil with asolution of potassium sulphate or nitrate removed its acidity, andalso 59 per cent. of its aluminium. The leached soil was bettersuited for the growth of clover than the original acid soil. Addi-tion of lime or calcium phosphate also overcame the acidity andmade the soil fertile.These facts are all consistent with the viewthat aluminium is the toxic agent. It is further suggested thataluminium occurs as gibbsite, a form of aluminium oxide, readilysoluble in acids, which during nitrification or " sulphofication ,"becomes converted into nitrate or sulphate. The weak point inthe suggestion is that neither gibbsite nor other readily solublealuminium oxide has commonly been found in soils in temperateclimates, although it must be admitted that they have rarely beenlooked for.An interesting test for sour soils is based on the fact that ironalso, like aluminium, passes into solution when a potassium saltis added to a sour soil, but not when it is added to a normalneutral soil. Sourness therefore is readily detected by addingpotassium thiooyanate, and still better by using an alcoholic solu-tion of this substance.14Soil acidity is now measured by: (I) the lime requirement orpotassium nitrate extraction,l5 essentially titration methods indicat-l1 See L.P. Howard, Soil Sci., 1919, 8, 313; A., i, 416.l2 For further evidence of the chemical origin of soil acidity, see H. A. Noyes,J . Ind. Eny. Chem., 1919, 11, 1040; A., i, 211, and R. E. Stephenson, S o 4Sci., 1919, 8, 41; A , , i, 274. For details see E. T. Wherry, J. WashinytonAcad. ScE., 1920, 10, 217; A., ii, 400.Is J. J. Mirasol, Soil Sci., 1920, 10, 153; A., 1921, i, 88.I4 N. M. Comber, J. Agric. Sci., 1920, 10, 420.l5 H. G. Knight, J. Ind. Eng. Chem., 1920,12, 340 ; A., i, 468.For a studyof lime absorption by Indian soils and a method for muertaining lime require-ment, see F. J. Warth and M. P. Saw, Mem. Dept. Agria. India, 1919, 5, 157 iA., i, 416AGRIOVLTURAL ~ M I S T R Y AND VEQETABI;B: PHPSIOLOUY. 179ing the quantity of the acid; (2) the hydrogen-ion concentration(Sorensen’s PH notation is commonly used),ls measuring thestrength or intensity of the acid. On general grounds one wouldexpect no necessary relationship between these quantities. As amatter of fact, it is now suggested17 that they may be related,the observed inconsistencies arising from inaccuracies in the Veitchmethod commonly used in Amerioa, or from the presence of“ buffers.” Seeing, however, that “ buffers ” occur in all soils itwould appear that exceptions would be frequent.It has sometimes been asserted that the acidity of soil is toofeeble to cause injury t o plants, and the cause of the infertilitymust be sought elsewhere.A set of measurements made in West Virginia 18 give the follow-ing optimum PH values when phosphoric acid and sodium hydrateare the adjusting substances: seedlings of wheat, soja beans andlucerne, 5-94; seedlings of maize, 5.16.In more strongly acidsolutions of soja beans and wheat suffered little until the value fellbelow 5.16; although lucerne suffered a t once, 2.96 seems t o bebelow the critical value, and 2-16 was fatal to growth (although notto germination) and favoured the growth of moulds in the oultures.Some injury was observed when the neutral point was attained andconsiderable injury when it was passed ; alkalinity apparently ismore harmful than acidity.Other measurements have been madewith lucerne a t New Jersey, sulphuric acid and calcium carbonatebeing here the adjusting substances. Germination was practicallyunaffected between PR values 4.5 to 7.0; below 4.5, however, it wasmuoh retarded.19 The yield showed a steady increase between P,values 3.8 to 6.5, with some irregularities between 6.5 and 8.More measurements of this kind are needed ; these results suggestslight acidity as the optimum condition, whereas long agriculturaltradition favours neutrality attained by use of chalk or lime.There is one case, however, where slight acidity is known tobe desirable-the potato crop, which becomes liable to “scab ” ifthe P, value is too high.Gillespie gave 5.2 as the limiting value;a case is now known, however, where “scabbing ” occurred at 4.8,although it was much reduced in comparison with the control plota t 5.6.20 Acidification had been brought about by the addition ofsulphur, which oxidises in the soil t o form sulphuric acid. Thismethod of controlling soil reaation promises to be of much interest.The student will find a full account of this method and a critical discus-sion by E. A. Fisher in J . Agric. Sci., 1920,11, 19,I f A. W. Blair and A. L. Prince, Soil Sci., 1920, 10, 253.ly J. 5. Joffe, Soil Sci., 1920, 10, 301.R. M. Salter and T. C. McIlvaine, J . Agric. Res., 1920, 19, 73.I0 W. H. Martin, ibid., 1920,9, 393180 ALMQUBL REPORTS ON TEE PROGRESS OF CHEMISTRY.Attempts have been made to ascertain in what way the acidityinjures plants.The acidity of the sap corresponds with values5-48’ to 5.97 in buckwheat seedlings, and 4.82 in the adult plant;%’there is also considerable reserve acidity.These figures may be of the same order as those for optimumconditions in the soil. Some of the results lend colour to the sug-gestion 22 that the harmful effect of soil acidity exceeding thesevalues is due to its influence in preventing plants from securingrapidly enough the bases necessary for neutralisation and precipita-tion of acids within the plant; in general, also, the addition of limeto the soil deareases the acidity of the plant juice.The present position cannot be better described than in thewords of D.R. Hoagland,B one of the foremost investigators ofthe modern aspects of soil problems :“ I n perhaps the majority of cases the inhibition of crop growthfrequently associated with acid soils may not be the direct effectof the acidity a t all. In other factors, such as soluble aluminium,may be found the true direct cause of the injury. It is grantedthat these causes may be removed by exactly the same treatmentwhich neutralises the acidity, but in the interest of saientific pro-gress it is essential to separate and designate the various factorsand their inter-relations.“Is it not possible that the whole subject would become clarifiedif we attempted to reach such definite conclusions as: ‘ The growthof the crop is inhibited by too great concentration of hydrogenion, or by too large a concentration of aluminium ion, or by toolow a level of calcium in the soil solution, or by the effect of thehydrogen-ion conaentration on the soil micro-organisms, etc.’ ? ”Methods of Increasing the Stock of Organic Matter in the Soil.Considerable attention has been given to green manuring as ameans of increasing the supplies of organic matter in the soil.Emphasis has again been laid on the value of leguminous crops,and some precise data have been accumulated.24 Attempts (unf or-tunately not giving very definite results) have also been made toascertain whether or not soil acidity is increased thereby.%Further evidence is published that in Virginia, as elsewhere, thegrowing crop temporarily restricts nitrification in soil, soja beansbeing an exception.2621 A.R. C. Haas, So2 Sci., 1920, 9, 341.24 E. Truog, ibicl., 1918, 5, 169.34 T. L. Lyon, J. A. Bizzell, and B. D. Wilson, Soil Sci., 1920,9, 53.25 L. P. Howard, ibid., 27.za Private communication.26 R. C. Wright, ibid., 1920, 10, 259AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 181Soil Organisms.The effectiveness of leguminous orops arises from the fact thatthey are associated with micro-organisms capable of fixing gaseousnitrogen and converting it into substances available for the nitro-genous nutrition of the plant. These remarkable organisms havebeen the subject of much investigation; a life-cycle has been sug-gested,27 for which there is considerable evidence.Five stages aredescribed : a small non-motile form, a larger non-motile coccus,an elliptical highly motile form (this being the swarmer stage ofBeijerinck), a rod form, and finally, when the carbohydrate supplyis exhausted, a vacuolated stage. A neutral reaction and thepresence of calcium phosphate speed up the change from non-motileto motile forms. This work is being continued.Some interesting work on the general biological relationships isbeing done in Professor A. L. Whiting’s laboratory in Illinois.The process of nitrogen fixation was not adversely affected bynitrate or by organic matter; indeed, in the case of cow peasthere was some evidence that the addition of organic matterincreased it .28Another important practical problem has been studied : whetherthe organisms are the same for all leguminous plants or whetherthere are special strains for each kind.Some degree of specificityis proved: the organism of lima bean (Phaseolus lirnatus) isidentical with that of cow pea and will inoculate either crop, butit is distinct from that of navy and kidney beans (Phaseolusvulgaris), and will not inoculate these.29Soja beanstake up these compounds readily from the soil; indeed, the con-oentration of nitrate in the cell sap becomes greater than in thesoil solution, and so high as to inhibit growth and reproduction ofthe organism there.30In addition to the fixation of nitrogen, bacteria play an importantpart in breaking down the protein contained in plant residues andproducing nitrates needed for plant nutrition.Further data havebeen collected in New Jersey showing that the productiveness isclosely related to the rate of evolution of carbon dioxide (described)as “oxidising power”), and to a less extent to rate of nitrateaccumulation and bacterial numbers.31In a suggestive paper, which may foreshadow important develop-Nitrates have a marked effect on nodule production.27 W. F. Bewley and H. B. Hutchinson, J . Agric. Sci., 1920, 10, 144.28 W. A. Albrecht, Soil Sci., 1920, 9, 275.A. L. Whiting and R. Hmsen, ibid., 1920,10, 291.W. H. Strow-d, ibid., 343. 91 J. R. Neller, aid., 29182 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.ments, Gillespie draws a distinction between oxidations of highpotential and those of low potential in a soil.s2 A given.rate ofabsorption of oxygen or production of carbon dioxide may arisefrom an oxidation of high intensity or potential involving a smallquantity of material, or a reaction of low potential involving mu&material. The phenomena are parallel to those of the hydrogen-ion concentration, and simultaneous development of both aspectsof the subject may be expected.Further work has been done on the protozoan fauna of the soil,and a t last it appears that this subject is being put on a soundbasis. The method of estimating the numbers of protozoa innatural soils has been greatly improved by D. W. Cutler a tRothamsted ;33 active forms can now be distinguished from cystsand separated out into a number of different species.The firstsystematic census34 was taken a t intervals of ten days, and theresults when plotted, whilst definitely indicating certain relation-ships, showed many fluctuations which were difficult to understand.A daily count of the organisms in a field plot was thereforeorganised, and it revealed some remarkably interesting phenomena.The numbers of bacteria were always inversely proportional tothe numbers of active amaebs, whilst the numbers of flagellatesshowed a remarkable periodicity which is not yet explained. Theresults35 are so important that tlie daily census is being continuedfor 365 consecutive days. American investigators have sometimesclaimed that protozoa were absent or unimportant in Americansoils, which if true would’ indicate a great difference in micro-organic flora in this country and America.Using a less completemethod of counting, it is now recognised that in the soil of NewJersey there is a ,fauna of organisms ‘‘ which are practically alwayspresent in the soil in considerable numbers and which use the soil asa medium in which to live and carry on their life processes.” Thefauna, however, is believed to exist mainly in the non-trophicstate.36 It seems highly desirable that an extended quantitativesurvey should be made in a t least as comprehensive a manner as isdone at Rothamsted, discriminating carefully between active formsand cysts; there appears to be no simple direct method of doingthis short of actual counts.Advances in soil microbiology have shown that the soil popula-tion is more complex than was a t one time thought, but it is alsoknown that some degree of simplification often increases productive-3p L.J. Gillespie, Soit Sci., 1920,9, 199.33 J . Agric. Sci., 1920, 10, 135.35 D. W. Cutler and L. M. Crump, Annals of Applied Bwl., 1920,7, 11.86 C. R. Felleria and F. E. Allison, SoiZ Sd., 1920,9, 1.84 L. M. Crump, ibid., 182AURICULTURAL CHEMISTRY AND VEUETABLE PHYSIOLOGY. 183ness. Simplification is obviously advantageous when diseaseorganisms or pests are present. Some organisms tend normally todisappear in the general competition ; the Yseudomonas citri caus-ing citrus canker in America is rapidly exterminated fromordinary soil, although it flourishes in sterilised soil? In othercases, however, competition alone is insufficient and direct controlis attempted.Heat is found to be effective, but its application israrely feasible. Recourse is therefore had to chemical methods,and substances are sought which, whilst toxic to the organism inquestion, will not injure the plant. This necessary limitation rulesout most inorganic poisons, such as arsenic compounds, mercurysalts, etc., and restricts investigators to organic substanoes.Applications to the soil of calcium sulphide and naphthalene orcymene lead to much increase in the crop and also in numbers ofB . butyricus, although on fallow soils this particular anaerobicorganism does not develop, but there is a loss of nitrogen.38In seeking for new agents the first step is to ascertainthe effect of various groupings on toxicity.In the caseof the wireworm 39 aromatic compounds are more toxicthan aliphatic compounds, and the toxicity is successfully increasedby the addition of methyl (the least effective), halogen, hydroxyl,or methylamino-groups (most effective). Substitution in the side-chain is more effective than in the ring. The effect is not additive,however; position and other groups both exert great influence.The association of chlorine and nitro-groups is particularly potent,and chloropiarin is one of the most lethal agents tested. In seriesof compounds of the same chemical type there is a fairly close rela-tionship between toxicity and vapour pressure, rate of evaporationand volatility, toxicity increasing as the volatility decreases, untilfinally, a limit is reached when the vapour pressure sinks too lowto allow of the attainment of a toxic concentration.Somewhat similar, although less extensive data, are recorded) withParamoecium .40A substance highly toxic to the organism, however, will notnecessarily suppress it in the soil, as the soil population indudesorganisms able to effect remarkable decompositions, for example, tobreak down such unlikely substances as phenol, cresol, and appar-ently even naphthalene and more stable ring compounds.Owing37 H. A. Lee, J . Agric. Sci., 1920, 19, 189; H. R. Fulton, ibid., 207.38 G. T d a u t and N. Bezssonoff, Compt. r e d ., 1920,171, 268 ; A., i, 655.sg F. Tattersfield and A. W. R. Roberts, J. Ag&. Sci., 1920, 10,199. Amongpossible agents, trichloroethylene deserves consideration : E. Salkowski,Biochem. Zeitsch., 1920,107, 191 ; A., i., 794, shows that it is cheap, volatile,and effective.‘O N. McCleland and R. A. Peters, J . PhysiOZ., 1919, 53, Xii, xv ; A., i, 512184 ANNUAL REPORTS ON THE PROURESS OF CHEMISTRY.t o the smallness of the amounts involved and the complex natureof soil, it is difficult t o ascertain the course of the decomposition,but some help may be obtained from the work of chemists on thecatalytic oxidation of simple but stable organic compounds.41The case of vanillin has been studied in some detail.*2 Thissubstance has been isolated from s0ii,~3 and it is toxic t o plants;it is, however, decomposed by certain soil bacteria.Apparentlyonly a limited number of organisms have this power. It is obviousthat micro-organisms capable of breaking down potential planttoxins are of importance in soil fertility.A further unexpected change apparently brought about bybacteria is the oxidation of the element sulphur when added to thesoil. This was first demonstrated in 1916,44 and’ was turned topractical account in the conversion of mineral ph Tsphates intosoluble phosphate in compost heaps or in the soil. Further detailsare now worked out, and it is shown that nitrification still pro-ceeds in spite of the formation of acid.45An interesting observation has been made in Egypt t o the effeotthat the fallow or “sheraqi” is a period of biological inactivityin the soil, but is followed by a period of increased activity, thephenomena being apparently parallel to those shown during partialsterilisation of the ~0il.46In some cases, probably in many, a reaction is brought aboutby a chain of agencies, chemical and biological.Thus, calciumcyanamide is a well-known fertiliser, but it owes its effectiveness tothe ammonia produced in its decomposition. The first stage is theproduction of carbamide ; this is apparently non-biological, since itoccurs even after the soil is heated to 135O; the decomposing agentis not yet identified, although the change can be brought about bycertain zeolites which may occur in soil. The second stage is theformation of ammonia from the carbamide; this is biological andcan be effected by numerous micro-~rganisms.~~An improved method, of determining ammonia in soil has beendeveloped.#41 For example, paraf6ns: A. Griin, Ber., 1920, 53, [B], 987; A., i, 518;benzene: J.M. Weiss and C. R. Downs, J . Id. Eng. Ciaem., 1920, 12, 228;A., i, 426.44 W. J. Robbins and E. C. Lathrop, Soil Sci.. 1919, 7, 475; A., i, 265 ;W. J. Robbins and A. B. Massey, ibid., 1920, 10, 237 ; A., i, 913.E. C. Shorey, J . Agric. Res., 1914, 1, 357 ; A., 1914, i, 916.44 J. G. Lipman, H. C. McLean, and H. C. Lint, So4 Sci., 1916,2, 499. Forbibliography, eeeH. C. McLean, ibid., 1918, 5, 251.45 0. M. Shedd, J . Agric. Res., 1919, 18, 329.46 J. A. Preacott, J . Agric. Sci., 1920, 10, 177.47 G.A. Cowie, ibid., 163; A., i, 655. 4s D. J. Matthews, ibid., 72AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 185The effect of water supply on bacterial aotivity has been studiedand some useful curves have been drawn; relationships have alsobeen traced with some of the Brigg's and' Hilgard's c0nstants.4~Relation of Soils t o Plant Growth: Water Supply.One of the most important functions of the soil is t o supply watert o the plant. This problem has been extensively studied by Living-stone, and he now contributes an important suggestion that mayhelp materially in elucidating the very complex phenomena con-cerned.50 The fundamental conception is t o regard the soil as amachine delivering water to the absorbing surface of the plantroots; the purpose of the investigation is to study the water-supply-ing power of the soil.The problem is regarded dynamically,although, of course, it depends on a number of statio conditions,such as sizes, kinds, and arrangement of the soil particles, and thewater content per unit volume. The experimental method consistsin embedding porous porcelain cones in the soil, then after a suibable time withdrawing them and weighing to measure the absorbedwater. Special attention is paid t o the region of moisture contentswhere wilting occurs. It appeared from the data obtained(although the authors frankly recognise their preliminary nature)that the water-supplying power a t the wilting point was approxi-mately the same for all the twelve soils examined.This criticalvalue is, of course, not to be regarded as a constant for all kinds ofplants and all degrees of evaporation, any more than is the wiltingcoefficient of Briggs and Shantz, which varies in a regular andpredictable way for any given soil and plant with the evaporatingpower of the air.61 I f further investigation confirms the view thatthe value is indepentdent of the physical make-up of the soil andis the same for sand, loam and humus, it will undoubtedly proveof importance.The power to supply water, however; is dependent on the amountpresent, and this is the balance of gains over losses. The loss ofwater from the soil takes place partly by drainage and partly byevaporation. It is claimed that the rate of evaporation isdiminished on addition of soluble salts, and the diminution isdirectly related to the osmotic concentration of the soil solution.@The water relationships for soils are very complex, and a valuablecritical resume of the whole subject has been made by Eeen.5349 J.E. Greaves and E. G. Carter, Soil Sci., 1920, 10, 361.B. E. Livingstone and R. Koketsu, ibid., 1920,9, 469.61 J. S. Calawell: The relation of environmental conditions to thephenomenon of permanent wilting in plants, Physiol. R c ~ . , 1913, 1, 1.M. I. Wolkoff, SoiZ Sci., 1920, 9, 409; A., i, 803.68 B. A. Keen, J . Agric. Sci., 1920, 10, 44186 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.An attempt has also been made to analyse more closely thecapillary movement of water through soil.54An important factor, determining not only water supply, buttilth, ease of working the soil, and other properties, is the degreeof flocculation of the finer particles.I n practice, lime is used toeffect this change, but the phenomena (do not altogether fall inline with those ordinarily observed with colloids. Some of theapparent contradictions are elucidated in a very suggestive paperby Comber. “Silt,” the fine but not the finest material in thesoil, is most easily flocculated by calcium salts when the suspensionis neutral ; this is the usual behaviour of insoluble substances.On the other hand, ( I clay,” the finest material, is most easilyflocculated in alkaline suspensions. This is unusual for insolublesubstances, but is shown by silicic acid and some of the so-called“emulsoid” colloids.It is suggested that clay as an emulsoidprotects the larger particles, which by themselves are suspensoid,and causes the whole soil to be flooculated by lime. I n absence ofclay, however, lime does not effect flocculation.55Alkali Soils.Under conditions of low rainfall, salts of sodium may accumu-late in soils and produce sodium carbonate by various interactions,which are not yet fully understood.56 It is suggested that thesulphate may in some cases be reduced to sulphide, which is thendecomposed by carbon dioxide to form the carbonate.57However they are formed in the soil, the harmful effeots ofsodium carbonate, sodium chloride, and other salts on plants andon organisms causing ammonification and nitrification are over-come by the addition of calcium sulphate.I n the case of micro-organisms, ferric chloride and sulphate are also eff ective.58Doubt is now thrown on the current values for the toxicity ofthese salts in soils. It is shown that soil absorbs more water froma solution of sodium carbonate than from an equivalentsolution of sodium chloride, and therefore, under conditionsapparently comparable, the plant root would be in contactwith a more concentrated solution of carbonate than of thechloride. This fact is said to have been overlooked, and to have54 W. Gardner, Soil Sci., 1920, 10, 103, 357.3 N. M. Comber, J . Agric. Sci., 1920, 10, 425. For other experiments, see56 For a recent discussion, see A.de Dominicis, Staz. sper. agr. Ital., 1918,57 E. Pozzi-Escot, Bull. SOC. chim., 1919, [iv), 25, 614; A., ii, 185.5g J. E. Greaves, Soil Sci., 1920, 10, 77.0. M. Smith, J . Amer. Chem. SOC., 1920, 42, 460; A., ii, 296.51, 103 ; A., i, 414AGRTCULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 187led to false conclusions as to the relative toxicity of thesesubstances.69Other Investigations.Further experiments are reported showing that calcium sulphateincreases the amount of soluble matter in soils.6O The amount ofwater-soluble material in the soil is not greatly affected by normalvariations from the mean moisture content, but it is reduced whenair-dry or water-logged conditions are attained.61Work on the drift soil of the Craibstone Farm has been con-tinued .62 This soil is largely composed of disintegrated granite.Like other soils, it has a marked power of absorbing ammonia, andthe property is not shown by all constituents alike, but chiefly bythe finer fractions.Powdered granite shows similar powers ofabsorption. It is not necessary to assume, therefore, that absorp-tion is effected only by decomposed material. Absorption isdecreased after ignition.Fertilisers.Following the practice of the previous years, the technical aspectsof this part of the subject will be discussed in the Report to theSociety of Chemical Industry, and only a few of the papers ofscientific interest will be referred to here.Two summaries of long-oontinued field experiments have beenissued. I n the New Jersey experiments, the best results were givenby sodium nitrate on the unlimed, and ammonium sulphate on thelimed, plots, whilst the organic manures (dried fish, dried blood,and tankage) were less effective. No more than one-third of theadded nitrogen was recovered in the crop, and, in absence ofleguminous plants, there was no accumulation of nitrogen in thesoil, but, on the contrary, a ~OSS? I n the Ohio experimentssummarised by Director Thorne, very similar results were obtained ;sodium nitrate proved better than ammonium sulphate on unlimed,but not on limed, soils, and both proved better than tankage.64One case is reported, however, where an organic manure provedmore effective than others, namely, that of the American ‘‘ blue-berry.” Sodium nitrate by itself somewhat depressed the yield ;59 T.H. Kearney, Soil Sci., 1920, 9, 267 ; A., i, 588.6o M. M. McCool and C. E. Millar, J . Agric. Rw., 1920,19, 47 ; A., i, 588.61 J. C. Martin and A. W. Christie, ibid., 1919, 18, 139.62 W. G. Ogg and J. Rendrick, ibid., 1920, 10, 333, 343.63 J. G. Lipman and A. W. Blair, Soil Sci., 1920, 9, 371.G4 C. E. Thorne, {bid., 487188 ANNU& REPORTS ON THE PROGRESS OF CHEMISTRY.complete artificial manure somewhat increased it, but a mixture ofthe latter and dried blood considerably increased it. Themanuring of fruit has, however, always been a subjeot of somedifficulty, bristling with exceptions to all the rules.65In all fertiliser work, it is necessary t o carry out field trials,and, in spite of their apparent simplicity, they are liable to manysources of error.A useful summary has been prepared: of themethods by which the more serious errors can be avoided, specialstress being laid on Larsen's method.66 .The effect of magnesium carbonate on plant growth is a subjectof much practical importance; a persistent idea is current amongpractioal men that it is in some way harmful to crops, and, inconsequence, magnesium limestone is not held in high repute.Many experiments have been made. Recently, in Indiana, magne-site proved more favourable than caicite for nitrification and formultiplication of aerobic and anaerobic bacteria on a yellow claysoil, but not on a black soil; it produced a greater increase insoluble salts in the soil, and led t o larger increases in yield of beet,but smaller increases of wheat and clover, than did oalcite.67 Onthe other hand, i t is elaimed that full crops are not obtainable onsoils where magnesia is in excess of lime.s8Plant Growth.The nutrient salts absorbed by plants from soil, together withthe carbon dioxide assimilated by their leaves, are elaborated intothe complex constituents and contents of the plant cells.Theprocesses involved continue to form the subject of much investiga-tion. The relationships between absorption of salts by the plantroot and composition of the nutrient medium is being studied a tthe California Experimental Station, where, in the case of barley,three distinct phases in the absorption of the nutrients werefound.69 Up to the time of formation of the head, the rate ofabsorption progressively increases until, finally, the amounts ofnitrogen and of potassium reaoh a maximum.The second phasecorresponds with the translocation of material into the developingheads; this is marked, not only by a decreased rate of absorptionfrom the soil, but by definite and substantial losses of nitrogen,potassium, and apparently calcium from the aerial parts of the65 C . S . Beckwith, SoiZSci., 1920, 10, 309.66 J. Sebelien, J . Agric. Sci., 1920, 10, 416.$7 S. D. Corner and H. A. Noyes, J . Agric. Rea., 1919, 18, 119.68 J. Hughes, J . Bzth and W. and S. 00. Soc., 1919, [v], 13; A., i, 416.69 J. S. Burd, J . Agric. Res., 1919,18, 61ABBRICULTURAL CHEMISTRY AND VEGETABLE mYSIOLOBBY.189plant, and presumably from the whole plant, although difficultiesof manipulation make root examination uncertain, Towards theend of the period, the lost materials are regained. The final stageis ripening, during which absorption ceases and losses are resumed.It is suggested that these movements of salts into and out fromthe plant may be due t o purely physical causes, as low concentra-tion of the water extract of the soil occurs simultaneously with themovement out from the plant. The results suggest that the normalrelationship between plant and soil is to have a relatively high soilconcentration in the early stages of growth and a low ooncentrationin later stages.Reference has been made in earlier Reports t o the work of Shiveand Tottingham, in which it is claimed that plants need not onlyan adequate supply of various nutrient substances, but also somekind of relationship or “ physiological balance ” between the par-ticular elements.The data show considerable variations, but theratio of nutrients causing maximum growth is called the optimumratio. This ratio is found t o alter with the concentration of thenutrient solution; it is not the same a t 0.1, 1.75, and 4 atmo-spheres,70 but it is unaffected by the nature of the medium, beingthe same in sand as in water culture. So also it is independent ofvariations in the moisture oontent of the sand, and is the same fordegrees of moistness varying from 40, 60, to 80 per cent. of thewater-retaining capaoity of the sand.It is not, however, constantfor the whole range of growth of the plant, being different inseedling and adult stages, and different for the growth of. “top”and of the roots.Closely associated with this conception of physiological balanceis that of antagonistic action between ions. Wheat seedlings areadversely affected by sodium ohloride and sodium sulphate, but thetoxic effects are largely overcome by small amounts of calciumoxide or calcium sulphate, and t o a less extent by magnesiumsulphate and barium chloride. The lime did not prevent theentrance of the sodium salts into the plant; its antagonistic effectwas therefore not attributable t o any reduction of permeability.71Calcium salts also enable the plant t o overcome the harmfuleffects of copper salts, although they do not prevent the entry ofcopper into the plant.It is considered more probable that thecalcium favours the evolution of the plant, giving it greater vigour,and in particular greater volume, into which the copper diffuses,thus preventing dangerous accumulation in any one region .7370 J. W. Shive, J . Agric. Rm., 1920,18,357.‘I L. Maquenne and E. Demoussy, Compt. rend., 1920,170,420; A., i, 857.J. A. LeClerc and J. F. Breamale, ibid., 347; A., i, 413190 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Attention has, however, been directed to the possibility thatcertain ions may alter the plasma colloids 73 or the permeabilityof the plant cells.74 Ferrous salts are known t o be more injuriousto young plants than ferric salts, and therefore any conditionwhich favours their oxidation reduces the toxic effects. It is shownthat monopotassium phosphate and copper sulphate both have thiseff ecL75 Neither manganese sulphate nor chromium salts were foundeffective as f ertilisers.76The functions of the various nutritive elements are determinedindirectly. Some work has been done this year on calcium.77There seems to be a close relationship between the calcium andnitrogen content of plants, and the more important crops can bedivided into two groups: (a) those with low content of calciumand nitrogen, a low calcium-nitrogen ratio, and low lime require-ments; ( b ) those with high content of calcium and nitrogen, highratio, and high lime requirement.It is suggested that proteinmetabolism is probably one of the ahief sources of plant acids, andmay give rise t o the need for calcium.The question whether silicon is necessary for plant nutrition hasbeen raised. An artificial calcium silicate was tested againstcalcium carbonate, and found to be in no way superior. Itappears, therefore, that silicon in this compound is of no advantageto the growing crop.78An interesting and entirely novel suggestion as to the functionof potassium in plants has been brought forward. It is claimedT9that the potassium ion may, as regards function, be replaced byall the other radioaotive elements, heavy or light, provided thedoses are equiradioactive; it may also be replaced by a free radio-active radiation.Some attention has been given to the action of copper salts onvegetation.It is shown that copper is a frequent, and possiblya normal, constituent of plants.80 It is claimed, in spite of7s T. Tadokoro, J . ColE. Agr. %okkaido. Imp. Univ., Sapporo, Japan, 1919,8, 143; A., i, 585; S. M. Neuschlosz, Pjliiger’s Archiv, 1920, 181, 17; A.,i, 698.74 0. L. Raber, J. gen. Physiol., 1920, 2, 535, 541 ; A., i, 585, 586.75 L. Maquenne and E. Demoussy, Compt. rend., 1920,171, 218; A , , i , 654.76 T. Pfeiffer, W. Simmermacher, and A. Rippel, Fuhlings Landw. Zeit.,1918, 313 ; A., i, 652 ; F. Weis, K. Vet.-Landboh6jskole Aarsskrijt, 1919,239 ; A., i, 652.77 F. W. Parker and E. Truog, Soil Sci., 1920, 10, 49 ; A., i, 702.78 B. L. Hartwell andF.R. Pember, ibid., 57.79 H. Zwaardemaker, J. PhySiol., 1920, 53, 273 ; A,, i, 511 ; Pfliiser’e Archiv,80 E. Fleurent and L. L6vi, BuU. SOC. c h h . , 1920, [iv], 27, 440, 441 ; A.,19 18,173, 28 : A., i, 345.i, 584AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 191previous work to the contrary, that dilute solutions of coppersulphate added to water cultures have a favourable action on thegrowth of roots and stems of peas and wheat.81Theoretical discussions have been attempted 82 of the physico-chemical basis of the phenomena of absorption and elaboration ofnutrient salts, and of the effects of these salts on cell division.83For many years i t was supposed that nitrates, phosphates, andsimple salts of potassium, calcium, magnesium, etc., were alonenecessary to plant growth, no organic compound of any kind beingrequired.Recently i t has been asserted that certain organiccompounds are helpful, if not necessary, and lead to markedincreases in growth. The case of Lemma major has been studiedin London ; crude nucleic acid derivatives from bacterised peat,the growth products from Azotobacter chrococcum and Bacillusradicicola, leaf mould, fresh and well-rotted stable manure, andwell-manured fertile soil all contained water-soluble substanceswhich promoted the growth of this organism.84 I n California,dilute extracts of peat (10 parts in 1,000,000 of water) produceda marked stimulation of root growth of citrus seedlings,85 whichcould not be obtained with oorresponding solutions of sodiumnitrate or potassium chloride.On the other hand, bouillon pre-pared from fresh brewers’ yeast, which had been heated to 1 3 5 Oand rendered incapable of curing polyneuritis in pigeons, was stilleffective in improving the growth of fungi.86Assimilation.-The ease and rapidity with which the plant insunlight absorbs carbon dioxide and converts it into sugar hasalways been a source of wonder to chemists, who have never yetbeen able to reconstruct the process.Support is periodically forthcoming for Baeyer’s old hypothesis ;it is claimed87 that formaldehyde can be absorbed by plant leavesand transformed into plant tissue. There are, however, diffioultiesin the way of this hypothesis, and another has been put forward,which is claimed to be more in accordance with the facts.Thefirst stage is supposed to be the isomerisation of carbon dioxide,with the formation of a secondary peroxide, >C<g2H ; thisL. Maquenne and E. Demoussy, Compt. rend., 1920, 170, 1542; A.,i, 584.aa E. Reinau, Zeitsch. Elektrochem., 1920, 26, 329; A., i, 799.83 J. Spek, Koll. Chem. Beihefte, 1920, 12, 1 ; A., i, 853.84 W. B. Bottomley, Proc. Roy. SOC., 1920, [B], 91, 83; A., i , 265; I?. A.Mockeridge, Biochem. J., 1920,14, 432 ; A., i, 704.35 J. F. Breazede, J . Agric. Res., 1919, 18, 267.96 A. Lumibre, Compt. rend., 1920,171, 271 ; A., i, 652.M. Jacoby, Biochem Zeitsch., 1919, 101, 1; A., i, 800192 ANNUAL REPORTS ON WitE PROQRESS OF CHEMISTRY.HO-C-OH o=c=o HO-C-OH ‘..*+2H, 0 + --t s*j\..*HO-b-OH HO-C-b o=c=oH eliminates oxygen and yields the group which is pre-+o,88 G.Woker, PfEiiger’s Archiv, 1919,176, 11 ; A., i, 354.*@ P. R. Kcgel, Zeitsch. wise. Photochem., 1920, 19, 215; A., i, 355.go 0. Warburg, Biochem. Zeitsch., 1919, 100, 230; 1920, 103, 188; A.,91 R. Wurmser, Compt. rend. SOC. Biol., 1920, 83, 437 ; A., i, 560.92 K. Stern, Ber. Deut. bot. Ges., 1920, 38, 28; A., i, 700.93 E. Reinau, Chem. Zeil., 1919, 43, 339; A., i, 128.94 W. J. V. Osterhout, Bot. &z., 1918, 68, 60; A,, i, 128.96 M. B. Cummings and C. H. Jones, Bull., 1919, 211, 56 pp.; A., i, 267.i, 583, 798.See also F. Riedel, Stahl tcnd Eben, 1919,39, 1497AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 193carbamide,gG and it is certainly true that assimilation usuallyproceeds in this way.Periodioally, it has been assumedl thatgaseous nitrogen might be assimilated by higher plants, but thepossibility has not been taken seriously by physiologists. It isknown, however, that certain bacteria can effect this assimilation,and from gaseous nitrogen and carbohydrates can synthesis0 cellproteins; but these bacteria have no power of synthesising carbo-hydrates: they are dependent on pre-formed sources of thesematerials. Moore has made the interesting announcement thatcertain unicellular alga possess the power of fixing, not onlygaseous nitrogen, but carbon also, so that they can by themselves,and without pre-formed carbohydrates, construot the wholeorganic contents of their ~ells.~7 I f this result is confirmed, it willalter some of the fundamental conceptions of soil microbiology andplant physiology.The Growth of Plants: Effect of Light and Temperature.-Investigators dealing with the growing plant are soon compelledto realise the dominating effect of factors other than the supplyof plant nutrients.The rateof growth is directly proportional t o the length of the day, andthis factor also profoundly affects the sexual reproduction ofplants; in many species the flowering and fruiting stages can beattained only when the length of day falls within certain limits,for example, in natural conditions only during certain seasons.g*I n absence of sufficient day length, vegetative growth may continuemore or less indefinitely, thus leading t o the phenomena ofgigantism; or, on the other hand, under the influence of suitableday length, precocious flowering and fruiting may be induced.I nsome cases, a day length was found suitable both to vegetativegrowth and reproduction ; an ever-blooming or ever-bearing habitwas then obtained. By suitable variation of the length of day, itwas possible to give annuals a perennial habit, or, on the otherhand, t o hasten their processes, so that they would go throughtwo cycles of alternate vegetative and reproductive activity in oneseason. Variations in intensity of light had little effect, thenormal intensity, as shown by H. T. Brown, being more thansufficient for the needs of the plant.Moisture supply and temperature are equally important factors :these have been invoked t o explain the stunted growth in wind-One of the most important is light.% T.Bokorny, Pfliiger’s Archiu, 1918, 172, 466; A., is 413, shows that97 B. Moore and T. A. Webster, PTOC. Roy. Soc., 1920, [B], 91, 201; A.,O* W. W. Garner andH. A. Allard, J . Agric. Res., 1920,18, 563.REP.-VOL. XVII. Hcarbamide is utilisable in proper conditions.is 466194 ANNUAL REPORTS ON THE PROGRESS OR' CHEMISTRY.swept districts, evaporation being so marked that the plant isseriously aooled and deprived of adequate water supply. Whenthese factors are made good, wind does little harm to crop growth.99Itis shown that cereal seeds can withstand dry heat to a tempera-ture of, 100° for some hours without serious loss of germinatingpower, whilst some of the disease spores affecting seeds were killed.1Studies have been made on somewhat similar lines of wilt-producing fungi, temperature having been found which will keepthem in check without unduly damaging the plant.2Of the numerous specialised papers, two may be mentioned.Composition of Crops.Few problems present greater difficulty than those associatedwith the composition of crops. Farmers grow crops in order tosell them, but neither they nor the purchasers know what is inthem.Little is known of the composition of crops, and, unfortu-nately, it is proving very difficult to arouse any interest in thisor the closely allied subject of quality in crops.The oat crop is one of the most important to the farmer, and ithas been studied in detail by Berry a t the West of Scotland Agri-cultural College.3 A mass of analytical data is presented whichis by far the most extensive hitherto available in this country.Various relationships were found between weight and compositionof the kernel; with the thin, husked, white grains, as the kernelincreased in weight the proportion of husk decreased, the oil andfibre diminished, whilst the carbohydrates, the yield of grain, andthe proportion of grain to total produce increased. It is animportant practical observation that the yield per acre is associateddirectly with the average size of individual grains, whilst theproduction of straw varies in the opposite direction.The composition of the grain was affected by variation in organicmatter content of the soil, for example, ploughed-up grassland andarable land, but season produced comparatively little effect, andartificial fertilisers still less.Locality, however, had a markedeff eot .Investigations on the wheat crop on somewhat similar lines havebeen made at the University of Manitoba.4 I n an importantpaper it is shown that the protein content of wheat is much affectedby climatic factors, by restriction of water supply, and by varietal*@ L. Hill, Proc. Roy. Soc., 1921, [B], 92, 28.1 D. Atanasoff and A. G. Johnson, J. Agric. Em., 1920, 19, 379.2 H. A. Edson and M. Shapovalov, ibid., 18, 511.3 R. A. Berry, J. Agric. Sci., 1920, 10, 359.H. E. Roberts, J . Agric. Res., 1920, 10, 121AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY.195factors. I n breeding new varieties for general purposes, it issuggested that strains should be sought which vary greatly in theirprotein content, since a wide starch-protein ratio would probablymean greater climatic adaptability. For restricted areas, how-ever, wheats of maximum protein oontent should be sought. Thereduction of protein subsequent on irrigation can be largelycounterbalanced by introducing lucerne into the rotation.5Plant Constituents.Constant additions are being made to the long list of plant con-stituents, and little more than the briefest reference is possiblehere. Until the function of a substance is known, the mere factof its presence is not necessarily of much physiological interest.Cellulose, Lignin, e t c.-These substances constitute the largerportion of the material of the plant structure, and steady progressis being made with the knowledge of their constitution.6 Perhapsthe most important paper on this subject is a critical discussionof the constitution of cellulo~e.~ Lignin has also been the subjectof investigation; it has received the formula C,,H,,OI,, and issupposed to be built up from pentoses.8Plant Pigments.-Flauones are yellow pigments ; those obtain-able from the tulip9 and from Rhus10 have been studied.Anthocyanins are formed from flavones by reduction. The redpigment of the young leaves of the grape vine is regarded asidentical with enidin, the anthocyanidin derived from the pigmentof the purple grape. This is the first instance reoorded in whichthe red leaf pigment is an anthocyanidin.11Members of the beet-red group of anthocyanins have been foundin the skins of fuchsia and cacti berries, and in the petals of scarletcactus flowers.12Anthocyanins are further reducible to leuco-bases .The tinctorial properties of a number of the anthocyanins haveJ.S. Jones, C. S. Cohen, and H. P. Fishburn, J. Agric. Sci., 1920, 10, 290.P. Klason, Arkiv Kem. Min. Geol., 1917, 6, No. 15 ; A., i, 148.7 K. Hess and W. Wittelsbach, Zeitsch. EZektrochem., 1920, 26, 2 3 2 ; A.,8 P. Klason, Arkiv Kern. Min. Geol., 1917, 6, No. 15; A., i, 148.9 B. Harrow and W. J. Gies, Proc. SOC. Expt. Biol. Med., 1918, 16, 8 ; A.,10 C. E. Sando and H. H. Bartlett, Amer.J. Bot., 1915, 5, 112 ; A., i, 272.11 0. Rosenheim, Biochem. J., 1920, 14, 178 ; A., i , 467.F. Kryz, Oesterr. Chem. Zeit., 1920, 23, 5 5 ; A., i, 515.l3 A. E. Everest and A. J. Hall, J. Xoc. Dyers and Col., 1919, 35, 275 ; A . ,been studied.13i, 532.i, 70.i, 70.H 196 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Sugars and Other Carbohydrates.-An improved method fordetecting dextrose in plants has been described.14 Both gentianoseand sucrose have been detected in the roots of Gentiana cruciataand G. purpurea.16Primeverose has been isolated from Primula officinalis; it is abiose formed by combination of a molecule of dextrose and a mole-cule of xylose, and it has a free aldehyde group.16Inulin is the storage product in some plants, notably the arti-choke. It does not occur in the leaves, but is formed in the stemand the tuber, presumably from the dextrorotatory carbohydratessupplied to the leaves.17Odorous Constituents.-The odorous constituents of apples havebeen found to consist essentially of the amyl esters of formic, acetic,and hexoic acids, with a very small amount of the octoic ester,ansd, in addition, acetaldehyde, and probably some free acid.18Proteins.-Osborne has continued his work on plant proteins,and has turned to the difficult problem of the leaf proteins, spinachbeing selected for examination.At least 40 per cent. of the totalnitrogen of the leaves was found in the form of colloidal protein,which, however, may be in some form of combination with a sub-stance of pentosan nature.A nearly colourless protein was, how-ever, obtained.19Two globulins and an albumin have been extracted from theGeorgia velvet bean.20 Globulins have been extracted from thecoconut (Cocos nucif era) 21 and the jackbean (Canavalia ensi-formis),22 whilst phaseolin has been studied,23 and also the proteinsof polished rice.24Alkaloids.-Niootine is not present in the seed of tobacco; it is,indeed, harmful to germination, but it appears in the young plantimmediately the chlorophyll begins to function, and it originatesin the leaves. 1n case of injury, for example, cutting, the alkaloid]is produced in increased quantity in the adjoining tissues. It isl4 E. Bourquelot and M. Bridel, Compt. rend., 1920,170, 631 ; A., ii, 337.l5 M. Bridel, J . Pharm. Chim., 1920, [vii], 21, 306; A., i, 467.l6 A. Goris and C. Vischniac, Compt. rend., 1919, 169, 871, 975 ; A., i, 14.l7 H. Colin, Bull. Assoc. Ch7m. Sucr., 1919, 37, 121 ; A., i, 358.F. B. Power and V. K. Chesnut, J . Arner. Chem. Soc., 1920, 42, 1509;l9 T. B. Osborne and A. J. Wakeman, J . Biot. Chem., 1920, 42, 1 ; A.,zo C. 0. Johns and H. C. Waterman, ibid., 69 ; A., i, 515.21 G. 0. Johns, A. J. Finks, and C. E. F. Gersdorf, ibid., 1919, 37, 149;23 A. J. Finks and C. 0. Johns, ibid., 1920,41, 375 ; A., i, 401.24 J. Kurosawa, J . Tok3o Chem. Soc., 1919,40, 551 ; A., i, 414.A., i, 653.i, 516.A., i, 210, a2 J. B. Sumner, ibid., 137 ; A., i, 210AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 197supposed, therefore, that nicotine is elaborated by the plant fromcertain residues of the nitrogen katabolism, either to preventaccumulation of these residues or to utilise them with intensifi-cation of their harmfulness in defence of its organs.25Lyoorine, C,,H,,O,N, has been found in various plants of theorder Amaryllidacez.26Hydrogen Cyanide.-Considerable technical importance attachesto the occurrence of hydrogen cyanide in plants. This substanceusually occurs in glucosidal combination, as in bitter almonds,cherry laurel leaves, seeds of Phaseolus lunatus, etc. It may alsooccur, however, in non-glumsidal form, in the buds of the cherrylaurel and the young leaves of Sainbucus niger.27Enzymes.-It is not proposed to discuss here the generalproblem of enzyme activity, but reference must be made to onepaper. The peroxydasic function in plants, which appears to beshown by living cells only,28 and is usually attributed t o enzymes,now appears to be due to iron compounds, katabolic products ofmore complex compounds, such as naematoids, which, in virtue oftheir physical state, are able to aot between the oxidisablesubstances and the peroxides.29 E. J. RUSSELL.25 L. Bernadini, Atti R. Accad. Lincei, 1920, [v], 29, i, 62 ; +., i, 412.26 K. Gorter, Bull. Jard. bot. Buitenzorg, 1920, [iii], 1, 352; A., i, 467.27 L. Rosenthaler, Sciaweiz. Apoth. Zeit., 1919, 57, 571 ; A . , i, 271.J. G. McHargue, J . Amer. Chem. SOC.. 1920,42, 612; A., i, 406.29 G. Gola, Atti R. Accad. Lincei, 1919, [v], 28, ii, 146; A., i, 208