AGRICULTURAL CHEMISTRY AND VEGETABLEPHYSIOLOGY.ALTHOUGH 1919 will scarcely rank among the years of greatachievements in agricultural chemistry, it has been notable for somehighly promising developments. Chief among these, as far as thiscountry is concerned, is the intention of the Board of Agriculture,as announced in the Press, to set aside the sum of $2,000,000 foragricultural education and research during the next five years, ofwhich 32250,000 will be available for research. Although this sumdivided among ten or twelve institutions and spread over five yearsdoes not at the present value of money represent affluence, it is,nevertheless, a highly important advance on anything previouslyattempted in this country.Another significant event is the establishment by an importantagricultural company-the Olympia Co ., under the chairmanship ofMr. Joseph Watson-of a research laboratory under the able guid-ance of Professor C. Crowther, late of the Leeds University. Hehas already secured the services of two of the best of the youngermen, Mr. C. T. Gimingham of the University of Bristol Agricul-tural Research Station, and Mr. H. Hunter of the Irish Departmentof Agriculture. Apart from investigations incidental to its advisorywork for the Company, the department will be specially equippedfor work on animal nutrition, plant breeding, and problems of soiland plant nutrition.Soil In@ es t ;gat ions.The investigations on soil in recent years have fallen in the maininto three great groups, dealing respectively with (1) the solutionwith which the soil is moistened, (2) the population of micro-organ-isms living on the plant residues which form an important partof the soil, and (3) the bioche.mica1 conditions in the soil.Hithertothese investigations have been on widely different lines, but thereseems iiow the possibility of a closer approximation.The iniportance of the soil solution in the nutrition of crops was171 G" 172 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.first, adequately recogiiised by Whitney and Cameron, working inthe United St-ates a t Washington. The more recent work has beeindone a t the California Experiment Station. The general outlinesof the earlier work were given in last year's Report, and two furtherpapers have been published this year.A careful study has beenmade of the relation of the concentration and reaction of thenutrient medium to t'he growt>h of the plant.1 The rate of growthof barley in water cultures was found to increase with increasingconcentration up to a certain point, beyond which there was nofurther growth. The amount of substance absorbed, however,increased with the concentration to a greater extent and over alonger range than did the growth. Contrary to some of the previouswork, no sufficient evidence was found that plants require anyvery definite ratios of elements or ions; indeed, considerablelimits of variation seemed permissible so long as the total supplyand concentration of the elements were adequate. Working onrather different lines, and in soil instead of water cultures, J.S.Burd2 finds that the absorption of various nutrients by barleygrowing in soil increases rapidly up to the ninth week, and then areversal takes place, there being a loss of material from the aerialparts of the plant to the root, or even to the soil, although no actualtransfer to the soil can be definit'ely established. After the eleventhor twelfth week, however, there is a further absorption whichcontinues to the end of the growing period, when a further lossappears t o set in.The solution moistening the soil particles has been extracted byvarious methods, and it has also been studied in the soil by thefreezing-point, method, more particularly by Bouyoucos and hiscolleagues .3 Perhaps the most interesting paper on the subjectduring the year has been a discussion4 of the numerous dataalready accumulated.Previous investigators have shown t.hatthe soil solution in quartz sand and in very light sandy soilsobeys approximately the same law as dilute solutions, the freezing-point depression varying as the concentration. I n the case ofordinary soils, however, this rule does not hold, the freezing-pointdepression increasing more rapidly than the moisture content fallsoff. Boupoucoa explained the discrepancy by supposing that someof the soil nioistxire plays no part in the phenomena of the depres-sion of the freezing point, and he deducts from the total moistureD. R. Hoagland, J . Agric. Res., 1919, 18, 73.Ibid., 1919, 18, 61.G.J. Bouyoucos and M. M. McCool, Michigan Agric. Coll. Expt. StationTech. Bulls. 24, 31, 36, 37 and 42; also J . Agric. Res., 1918, 15, 331 ; A.,i, 115. 4 B. A. Keen, J. Agric. Sci., 1919, 9, 400AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 173a sufficient amount, which he calls the “unfree water,” to leavea balance of “free water” that will conform to the freezing-point law. Assuming the distinction to be valid, Keen showsthat a mathematical relationship exists between the “ free,” the“ unfree,” and the total water; one equation defines the relation-ship over the whole range. Exactly the same thing happened inregard to the rate of evaporation of water from soils; one equationthere also covered the whole range, and the various constants andcritical points announced by other workers were found to beequilibrium points only, and not breaks in the physical state of thewater in the soil.5The physical properties of the soil are determined by its peculiarstructure : a mass of small, hard, mineral particles of varying dimen-sions intimately associated with a sufficient quantity of colloidalmatter to impress colloidal properties on the whole.The relation-ships of adsorption to coagulation have been discussed by some ofthe Italian workers.6 Setting out from the obvious propositionthat mutual attraction occurs where particles and ions with oppo-site charges come into contact, resulting in the neutralisation ofthe charges and formation of absorption compounds, the authorsattempt to show that the consequent decrease in concentration, bothin colloidal and ionic-molecular solution, is f avourable to productive-ness.The phenomena in regard to protein have been discussed bythe Wilsons,i but they are not necessarily related to the soil pheno-mena. The problem has been attacked in another way in Germany.8A salt is allowed to act on a soil, and is then extracted with waterand tthe effect on the physical properties studied. Salts of univalentmetals, particularly sodium salts, damage the texture of the soil ;those of bivalent metals do not-. I n this case, however, the effectsare not so much those of the actual saltq as those produced by thesubsequent hydrolysis after the salt is washed away.An attempt h a been made9 to ascertain the effect of certaincolloidal substances on the growth of wheat seedlings in culturesolution.They acted adversely, reducing the concentration byadsorption. Colloidal silica, however, proved to be an exception,and caused an increase not only in growth but also in the amountof silica in the plant.J . Agric. Sci., 1914, 6, 456.* A. de Dominicis and P. Chiarieri, Staz. sper. agr. ital., 1917, 50, 451 ;J. A. Wilson and W. H. Wilson, J . Amer. Chem SOC., 1918, 40, 886;G. Hager, J . Landw., 1918, 66, 241.D. S. Jennings, Soil h’ci., 1919, 7, 201.A., i, 142.A., 1918, ii, 260174 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The Biochemical Changes in the Soil.The soil organisms draw their supplies of food material and ofenergy from the stores of plant residues contained in the soil.Thetwo most important constituents of the plant residues are the cellu-lose and the proteins; the former give rise t o the so-called humuswhich has important physical effects in the soil; the latter yieldammonia, which becomes subsequently oxidised to form the nitratesessential to the nutrition of the crop.The organism concerned in the decomposition of cellulose has beenstudied in the Rothamsted laboratories. It decomposes celluloseunder aerobic conditions with comparative ease. It more closelyresembles the epirochxts than the bacteria, ahd is therefore namedSpirochaeta cytophnga. It's vegetative growth takes the form of asinuous filamentous cell, which is very flexible, but only feeblymotile ; a.pparently it does not possess flagella.This filamentousform can pass through a number of phases, yielding finally sphericalbodies somewhat resembling spores, but differing in several impor-tant respects, so that they are called by a different name, sporoids.The organism requires combined nitrogen, which it prefers in theform of nitrates, ammonium salts, amides, or amino-acids. Peptoneserves in dilute solutions, but a toxic limit is soon reached, whilstths conventional nutrient gelatin and nutrient agar are bothunsuitable.The carbon requirements of the organisms can be met only bycellulose so fgr as is known. Npne of the sugars, alcohols, or salts oforganic acids has proved effective, and some were definitely toxic.Given a suitable simple nitrogen compound and its other require-ments, the organism is able energetically to decompose cellulose,producing, among other things, a pigment somewhat like carotin, amucilage which does not yield optically active compounds on hydro-lysis, and small quantities of volatile acids.It was shown that theproducts are suitable for the needs of Azotobacter and allow of theassimilation of gaseous nitrogen.The decomposition of the proteins is brought about by bacteriaand apparently also by fungi, although on the latter point evidenceis still scanty. Fungi have been isolated in considerable numbersfrom soils, and their behaviour towards culture media has beenstudied. Thus it has been shown1* that they decompose carbo-hydrates, absorbing ammonia and producing protein, although inabsence of carbohydrates they decompose protein, forming ammonia.It is argued that, moulds are likely to be unfavourable to soill o H.B. Hutchinson and J. Clayton, J . Agric. Sci., 1919, 9, 143.It S. A. Waksman, SoiZ8ci., 1918, 6, 137; A . , i, 116AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 175fertility, except perhaps in so far as the formation of enzymes in thesoil is concerned. The difficulty is that the fungi are a plastic groupwhich may behave in one way under one set of conditions, but quitedifferently under other conditions. Evidence, however, has beenadduced that fungi may be positively harmful.12Pending further investigations into the part played by the fungi,it is usual to confine attention to bacteria.In recent years baderi-ologists have been content to study “ammonification ” as a wholewithout much reference to the individual species of organisms con-cerned. A few attempts, however, have been made a t studying theindividual species. I n the United States H. J. Conn13 finds thatnon-spore formers predominate in the soil, thus confirming theobservations of Russell and Hutchinson a t Rothamsted; he con-siders that? spora-formers are scarcely active in the soil under normalconditions, and that ammonia formation is mainly brought about byncn-spore formers (Tech., 51). I n this he runs counter to theaccepted tradition, which is that the spore formers include some ofthe most active forms. Rilarchal had concluded that B.mycoideswas one of the most common ammonia producers in the soil. Conncontroverts this statement., and maintains that of the‘eight impor-tant ammonifiers studied by Marchal only one, namely, B. fiwirescensZip. (a non-spore former), is a typical soil organism.Of the true soil organisms two are described 14 which, whilst notvery numerous in unmanured soil, multiply vigorously on additionof farmyard manure and produce ammonia: Ps. fiuorescens and 2‘s.cnudatus. ‘These organisms are described in sufficht detail to allowof identification by other workers.It is fnrt’her shown15 that the ,4ctznomycetes form a considerableproportion of the soil organisms-no less than 17 per cent. in amedium soil, and a higher proportion in heavy soils or those richin organic matter.An interesting study has been made16 of the rate a t which nitratesaccumulate in Egyptian soils under natural conditions.Normally,the process yields more nitrate than the crop requires, which mayaccount for the usual ineffectiveness of nitrogenous manures on thecotton crop in Egypt. The rate of nitrification, however, was muchaffected by the moisture content of the soil-more, indeed, than byany other single factor-and the whole process apparently came tol2 E. B. Fred, Soil Sci., 1918, 6, 333.l3 N. Y . Cornell, Agric. Expt. Sta. Bull., 338, 1913 ; Tech. Bull. 51, 1916 ;l4 H. J. Conn and J. W. Bright, J . Agric. Res., 1919, 16, 313.l5 S. A. Waksman and R. E. Curtis, Soil Sci., 1918, 6, 300.l6 J. A. Prescott, J . AgriC.Sci., 1919, 9, 216.Tech. Bulls. 57-60, 1917, and 64, 1918 ; J . Agric. Res., 1919, 16, 313176 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.a standstill during the summer fallow, a time of low moisturecontent and high temperature. I n pot experiments there was morenitrate produced under fallow conditions than in the presence of agrowing crop, as has already been observed both in England andAmerica.It has always been supposed that the nitrogen cycle was compara-ti\ ely simpla, the soil nitrogen compounds being changed to nitrates,which, unless washed out of the soil, are then absorbed by plantsand built up into fresh protein compounds. The results of a long-continued soil experiment, at Rothamsted are now summarised, andshow 17 that this simple view is scarcely sufficient; the nitrate forma-tion in a poor, unmanured soil, so far as can be measured by thequantity washed out in drainage water, proceeds at a very slowlydiminishing rate for an almost indefinike period-certainly for morethan fifty years-and during this time it appears almost uniformover a period of, say, from ten t o fifteen years.The simplestexplanation of the phenomena is that the nitrates formed in any oneyear are not wholly available for the plant or for loss in the drain-age water; a part may be supposed to be taken up a t once by otherorganisms aucl converted into protein, which subsequently againnitrifies. Thus the whole of the nitrate can never be exhausted;the process is expressible by an asymptot.ic curve.This idea of animmobiliser will probably be found helpful in dealing with t,he soilphenomena.There is, however, a further complication in natural conditions.For convenience of investigation the decomposition of cellulose andof protein are studied separately, but in point of fact the two reac-tions proceed simultaneously in the soil and profoundly influenceeach other. It has already been shown that the organisms decom-pGsing cellulose require a supply of nitrate or other soluble nitro-genous compound. I n like manner organisms decomposing sugarapparently require nitrates, and there is, in addition, the possi-bility that they actually decompose nitrates with. evolution ofgaseous nitrogen or nitrogen compounds.Both these actions tend to loss of nitrogen.There is a third typeof action that tends to a gain of nitrogen. I n the presence of easilyoxidisable carbohydrates certain orgqisms can fix gaseous nitrogen,converting it into protein, which sub$equently decomposes and givesrise to ammonia, and then to nitrates.'Thus the addition of sugar or straw to the soil has a drasticeffect on the nitrogen cycle, the possibilities being a loss of nitrate intwo ways and a gain of protein in two ways-an absolute gain fromfree nitrogen and a relative gain from nitrate or ammonia. Whether1 7 E. J. Russell and E. H. Richards, J . dgric. Sci.,lQ19, 10, 14AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 177the net change will be a gain or less of nitrogen depends on circum-stances. Thus in recent experiments the addition of 2 per cent.ofsugar to soil was found 18 to diminish the first crop, but slightly toincrease the subsequent ones. Straw diminishes the crop for the firsttwo years, but gave a small increase in the third year; over thewhole period, however, the effect was negative.These various actions make it impossible to foretell the fate of agreen crop ploughed into the soil-a practice known as greenmanuring, common in this country, in India and elsewhere.I n a recent Indian investigation,lg the stems and ro0t.s of legu-minous plants were found to yield scarcely any nitsate, presumablybecause of the action of their non-nitrogenous constituents.Further, there were marked differelnces in the rates of nitrificat'ionof some of the oil cakes.20The importance of the changes effected by micro-organisms isso great that numerous attempts have been made t'o correlate soilfertility with bacterial activity, as indicated by rates of ammonifi-cation, nitrification, etc.Obviously correlation can be expectedonly when the nitrogen supply is a limiting factor in crop pro-duction, and even then regard must be had to the supplies in thesoil of protein compounds on which the organisms can act. Withthese limitations, however, some relationship between bacterialactivity and soil fertility is generally found. I n a detailed examina-tion of Hawaiian soils,21 the rate of ammonification afforded nosharp indication of fertility, as the differences between the g o d andthe poor soils, although in the right direction, were not sufficientlymarked.On the other hand, the rate of nitrification was a muchsafer index, and was, indeed, the most trustworthy of all themethods tested ; this experience has been obtained elsewhere.22This does not imply that the process of nitrification is responsiblefor the yield; it may be that both the plantl and the nitrifyingorganisms are limited by the same set of factors.EfJect of Salts.-The effect of inorganic salts on bacterial activityhas been investigated by Greaves and his colleagues at the UtahExpt. Station,23 where alkali soils present t roublesome problems.18 0. Lemmermann and A. Einecke, Landw. Vcrsuch.s-Stat., 1919, 93, 209.19 N. U. Joshy, Agric. J. I n d i a , 1919,14, 395.20 F.J. Plymen and TI. V, Ral, ibid., 414.21 P. S. Burgess, Soil Sci., 1918, 6, 449.22 For example, in Kansas by P. L. Gainey, ihid., 1917, 3, 399; -4.,1917, i, 529; in Pennsylvania, by G. P. Given, Penn. Rept., 1912-13, 204 ;in California by C. R Lipman and Burgess, CaZ. BUZZ. 260, 107 ; in Iowa byP. E. Brown, J . Agric. Res., 1916, 5, 855.28 J. E. Greaves, E. G. Carter, and H. C. Goldthorpe, J . Agric. Res., 1919,16, 107 ; A., i, 238178 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.The method consists in adding 2 per cent. of blmd meal to thesoil, then bringing up the moisture to 20 per cent., and finallyincubating at 28-30° for twenty-one days. The conditionsobviously are unnatural, and it would have been interesting tohave made the comparison also under normal conditions.Never-theless, the results are distinctly interesting. The effects of thevarious salts in depressing the activity of the ammonifyingorganisms are in the main similar to their action in depressingthe growth of wheat seedlings. The effect on nitrifying organisms,however, is more pronounced. The salts commonly occurring inalkali soils, sodium sulphate, sodium carbonate', and calciumchloride, are very toxic to bacterial activity, and hence thepossibility that part of the unsuitableness of an alkali soil forplant growth may lie in the depression of the essential nitrateproduction process.Nitrogen fixation is also affected considerably by thel presenceof dissolved salts.24 Sodium chloride in small quantities acted asa stimulant, but a t and above1 a concentration of 0.01 per cent.afalling off in activity occurred. Sodium nitrate, on the otherhand, caused distinct increase in the amount of fixation.The effect of salts appears to be specific, and not osmotic.Calcium sulphate markedly stimulates nitrification, as has beenobserved before under other conditions; so also' did sodiumchloride, magnesium carbonate, and sodium carbonate 25 in appro-priate concentrations, although beyond the proper limits harmfuleffects have been produced. On the other hand, calcium carbonatewas found to be toxic, an observation that deserves to be followedup in view of the known beneficial effect of this substlance onfe'rtility.The effect of nitrates on soil organisms is of special importance,because of the possibility that they may serve as nut,rients.Thenitrates of sodium, magnesium, manganese, calcium, and ironactively stimulate nitrogen-fixing organisms. They also stimulatecertain organisms which assimilate nitrat'es, transforming thenitrogen into protein ; thus, in the conditions of these experiments,they actually led to1 a decrease of nitric nitrogen in the soil.Further, Hutchinson and Clayton have found that they increasevery considerably the growth of the spirochzts which decomposecellulose. On the other hand, sodium nitrate appears to depressnitrification,26 but as i t caused a loss of nitrate from the medium,24 T. M. Singh, Sod Sci., 1918, 6, 463 ; A., i, 374.25 T. M. Singh, Zoc. cit., but Greaves obtained no stimulating action with26 T.M. Singh, Soil Sci., 1918, 6, 463; A., ii, 374.sodium carbonateAGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 179the effect may have been simply the, stimulation of nitrate-assimilating organisms already ref erred to.Numerous investigations have been made in the United Statesinto the effect of the chains of bacterial processes on the mineralconstitsuents of the soil. The nitrification of dried blood and thebacterial oxidation of sulphur in mixtures of sand and felspar areaccompanied by an increase in the amount of water-solublepotash; 27 the increase, however, is considered to be brought aboutby the salts formed, especially by ammonium sulphate, rahher thanby direct action of acid on the insoluble potassium compounds.Previous investigation has shown that both these changes, whencarrie'd out in culture solution,28 increase the solubility of rockphosphate.It is now shown 29 that no solvent action on phosphateaccompanies nitrification in the soil, nor did any accompanybacterial oxidation of sulphur, excepting in the case1 of acid soils.Ammonium sulphate, however, has little' or no solvent action onrock phosphatel, so that on the author's hypothesis the facts areexplicable.These secondary actions of substances on soil constituents havebeen invoked to explain some of the curious effects produced whenmixtures of fertilising constituents are used.30 Instances arequot'ed where an insoluble phosphate by itself was less effective asa fertiliser than a soluble phosphate, although on the addition ofsulphate of ammonia it became equally effective. There is somedisagre'ement as to the precise facts, but t-he possibility of thesesecondary actions seems worth exploring.An interesting suggestion has been made31 for the practicalutilisation of the bacterial oxidation of sulphur in soils.Potatogrowers prefer an acid soil, because acidity, whilst not unfavour-able to the potato crop, is entirely unsuited to the scab organism,32one of its worst pests. Ot,her crops of the rotation, however,especially clover, are injured by the acidity. It is pro-posed, therefore, that a dressing of 300 t'o 1000 lb. per acre ofsulphur should be made before planting the potatoes, to ensure therequisite degree of acidity, and, after the1 crop is removed, sufficientlime can be added t o ensure neutrality.An important addition to our knowledge of the soil protozoa has27 J.W. Ames and G. E. Boltz, Soil Sci., 1919, 7, 183.28 Hopkins and Whiting (Illinois Bull., 1916, No. 190, 395) state that 115parts of phosphorus become soluble in water for each 56 parts of nitrogenoxidised. These experiments were done in culture solution.29 J. W. Ames and T. E. Richmond, Soil Sci., 1918, 6, 351.30 J. E. Greaves and E. G. Carter, ibid., 1919, 7, 121 ; A., i, 564.31 J. G. Lipman, ibid., 181.s2 L. J. Gillespie and L. -4. Hurst,, ibid., 1918, 6, 219 ; A . , i, 115180 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.been made by D. W. C ~ t l e r , ~ 3 who has shown that these organismsadhere firmly t'o the soil particles up to a certain number per gramof soil, beyond which they no longer adhere, but can float away.Each of the soils examined had a definite saturation point.I f a soil is shaken with suspensions of protozoa of varying con-centrations, the absorption is complete in all cases where thenumbers are below the saturation capacity? but it is not extendedwhen the numbers rise beyond.Thus the phenomenon exactlyresembles in its sharpness the neutralisation of an acid with a base,and differs entirely from adsorption? which is not, in general, com-plete, but depends on the relative masses of the absorbed andabsorbing substances.The general biochemical conditions in the soil are frequentlyunder investigation as being equally important to the soil organismsand to the growing crop.Among the most important is the reac-tion of the, soil, whether Ecid or neutral, the acidity being measuredby the hydrogen-ion concentration and by some titration method.A large number of titrat<ion methods have been devised and tested,and new series of tests and new modifications have recently beenproposed.34 Criticisms of the sugar method described in last year'sReport have also been made.35 The soil acidity is found t o varywith the moisture conditions of the soil, but the variation isattributed to chemical rather than physical changes.36Aremarkable effect of farmyard manure on the clover crop will bementioned later. Another and wholly different effect is to reducethe harmful action of salts in alkali soils; 37 this is attributed t oadsorption of the salts by the colloidal substances of the farmyardmanure.A further important, effect, no doubt colloidal also, of organicmatter is to increase the water-holding capacity of the soil. Thisis clearly marked at Rothamsted, where 15 tons of farmyardmanure are added annually t.0 certain plots; it does not show, how-ever, in the Minnesota investigations, where only 5 tons of manurehad been added each four year~.~8I n view of these and other important properties, various meansof estimating the so-called humus in soil have been suggested from33 J .Agric. Sci., 1919, 9, 430.34 C. J. Lynde, Trans. Roy. Soc. Caizada, 1918-9, [Zl, 12, 111, 21 ; A.,ii, 376; L.P. Howard, Soil Sci., 1918, 6, 405; R. E. Stephenson, Soil Sci.,1918, 6, 37 ; E. T. Wherry, J. Washington Acad. Sci., 1919, 9, 305 ; A., i, 428.The supply of organic matter is of considerable importance.35 L. T. Sharp and D. R. Hoagland, Soil Sci., 1919, 7, 186.36 S. D. Conner, J. Agric. Res., 1918, 15, 321 ; A., i, 115.3 7 C. B. Lipman and W. F. Gericke, Soil Sci., 1919, 7, 105.38 F. J. Alway and J. R. Neller, J . Agric. Res., 1919, l6,-263AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 18 1time to time, a rapid test being the amount of chlorine liberatedfrom a solution of sodium hypochlorite.39The supply of mineral matter is of recognised importance, butless work than. usual has been done in recent years. The method ofusing weak acids for analytical purposes, general in this country,has been found satisfactory40 in Germany also.It has been shownthat the unsuitability of certain Minnesota prairie soils to legu-minous crops, vaguely attributed to (‘rawness,” is simply due tolack of mineral nutrients.41A study has been made! of the marked changes produced byheating the’ soil on its properties as a medium for the growth ofplants and organisms.@’Soil Constituents and So,il Siwveys.The soils of North Wales have been studied in detail during thepast few years.43 The sedentary soils of the carboniferous andmillstone grit formations, which occur in the drier parts of theregion, resemble those found elsewhere in t,hat the coarsest fractionsare the! richest in silica; they are, however, quite unlike thesedentary soils of the palzozoic series in the wetter districts wherethis rule does not hold.The organic phosphorus compounds 44 of soil and the aldehydes 45present in the soil have received some attention.Of the inorganic constituents, tthe clay is distinctly unfortunatein its name, inasmuch as the same word is used in a wholly differentsense by the ceramic investigators, whose work otherwise ought t obe very helpful t o soil investigators.46The chief chemical property of (‘ clay ” (using the word, not inthe ceramic, but, in the soil investigator’s sense) is its reactivitywith salts; i t readily exchanges bases.The action is not yet fully39 L. Lapicque and E. Barbe, Compt. rend., 1919, 168, 118 ; A., i, 116.4o 0.Lemmermann, A. Einecke, and L. Fresenius, Landw. Vtrsuchs-Stat.,1916, 89, 81 ; A., i, 616 ; 1 per cent. citric acid was used for estimationof the phosphate, and 10 per cent. hydrochloric acid for estimation of thepotash.41 P. R. McMiller, Soil Sci., 1919, 7, 233.42 J. Johnson, ibid., 1.43 G. W. Robinson and C. F. Hill, J. Ayric. Sci., 1919, 9, 259.44 C. J. Schollenberger, Soil Sci., 1918, 6, 365 ; A., ii, 168 ; R. S. Potter and45 J. J. Skinner, J. Fsranklin Inst., 1918, 186, 165, etc.46 See, for example, R. E. Somers (J. Washington. Acad. Sci., 1919, 9, 113),for a mineralogical examination of “ clay ” corresponding with “ fine sand ”and “ silt ” in soil work.R. S. Snyder, ibid., 1918, 6, 321 ; A., i, 142182 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.understood, and consequently soil investigators watch with interestthe work done on basic exchange in zeolites, silicates, etc., to seewhat light, if any, is thrown on their own problems.Among suchinvestigations may be mentioned those of Ra~llann,~T who fullyrealism the conditions obtaining in the soil.The various methods of soil analysis have been discussed andcompared by Richter .4*Rain.For many years agricultural chemists were very interested inthe composition of rain-water, particularly in the amount ofnitrogen compounds present, these being supposed to contribute tothe nutrition of the crop. It is now recognised that the quantitiespresent are too insignificant to exert any .appreciable effect, andthe long-continued series of analyses a t Rothamsted have been dis-continued.The results have been summarised .49 The ammoniacalnitrogen amounts on an average to 0.405 part per million, corre-sponding with 2.64 lb. per acre per annum; the yearly fluctuationsin lbs. per acre follow the rainfall fairly closely. The nitricnitrogen (which includes nitrites) is on an average one-half of thisamount, namely, 1.33 Ib. per acre per annum. There is a markeddifference in composition between summer and winter rainfall,suggesting that they may differ in their origin; the winter rainresembles Atlantic rain in its high chlorine and low ammonia andnitrate content; the summer rain is characterised by low chlorinebut high ammonia and nitrate content, suggesting that i t arises byevaporation of water from the soil and condensation a t higheraltitudes than in the case of winter rain.Whilst the subject hasno obvious agricultural interest, there is the possibility of a usefulcontinuation of the work in connexion with atmospheric pollution.It is interesting to note that the quantity of ammonia and nitratecollected in the rain at Ottawa50 is of the same order as a tRothamsted, namely, 0.46 part per million of free ammonia, 0.138as albuminoid ammonia, and 0.277 as nitrite and nitrate, making,with the organic nitrogen, 6-58 lb. per acre of nitrogen, as againsta little more than 5 a t Rothamsted. Very similar results wereobtained at Cornell,51 where the average free ammonia was 0'407,4 7 E. Ramann and A.Sprengel, Zeitsch. anorg. Chem., 1919, 105, 81 ; A.,i, 615. See also G. Kornfeld, Zei88ch. EZeEtrochem., 1917, 23, 173; A.,ii, 459 ; I. Zoch, Chemie der Erde, 1915, I, 55 pp. ; A., ii, 470.4 8 G. Richter, Int. Mitt. Bodenlcunde, 1916, 6, 193, 318 ; A., 1918, ii, 280.4 9 E. J. Russell and E. H. Richards, J . Agric. Sci., 1919, 9, 309.5 0 F. T. Shutt and R. L. Dorrance, Trans. Roy. SOC. Canadu, 1917-18,61 J. E. Trieschmann, Chem. News, 1919, 119, 49 ; A., i, 511.[iii], 11, 63 ; A., i, 116AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 183the albuminoid ammonia 0.366, the nitrate 0.255, and the nitrite0.018 part per million respectively.Fertilisers and Xanures..I n the main, investigations this year have been concerned withdetails of importance to the technical chemist and the agriculturaladviser; they are dealt with in the Report to the Society ofChemical Industry, and need not, therefore, be discussed here.The organic manures have been under investigation, and one ortwo conclusions of general interest have emerged.Farmyardmanure has been shown52 t o exert a beneficial effect on the growthof clover, appareatly greater than its composition leads one t oexpect; this result may be related Lo the life-cycle of the organism,which is now under investigation.Other organic substances used as manure include rape cake (theresidue left after the extraction of oil from rape seed); this con-tains a considerable proportion of plant protein, the decompositionof which in the soil gives rise to nitrates.It is often supposedthat plant or animal proteins must necessarily be more useful asfertilisers tlhan nitrates ; this anticipation does not appear to hecorrect.53An investigation has been made into the power of calciumsulphate to “fix” part of the ammonia liable to be lost frommanure heaps ; 64 whilst this shows that some degree of conservationmay be possiblel, it does not throw light on the1 fertilising value ofthe mixture of farmyard manure and calcium sulphate. I n thecase of liquid manure, gypsum was only partly effective.55Sulphates are not regarded as fertilisers in this country,although considerable quantities are, as a matter of fact, appliedto crops in the form of ammonium sulphate and superphosphate.It is known, however, that sulphur is essential t o crops, and aninteresting case is recorded from Oregon 56 of soils respondingmarkedly to sulphur and sulphates, larger returns having beenobtained from gypsum than from lime.Both sulphur andsulphates gave increased yields of oats, rape, and red clover, andin the latter case they led t o more nodule formation.6H E. J. Russell, J . Bd. Agric., 1919, 26, 122.53 Idem., ibid., 228.54 F. E. Bear and A. C. Workman, Soil Sci., 1919,7. 283 ; A . , i, 511.6 5 0. Lemmermann and H. Weissmann, Landw. Jahrb., 1918, 52, 297.6 G H. Q. Miller, J . Agric. Res., 1919, 17, 87 ; A., i, 510184 ANNUAL REPORTS ON THE PROGRESS O F CHEMISTRY.Z’he ,4bsorption of Nzitrients by t h e Plant Roots.The nutrient materials derived from the soil are absorbed bythe root, and numerous investigations have been made into themechanism of the process.W. Stiles and F. Kidd57 measured thechanges in conductivity of the solution of a salt presented to theplant tissue; these were taken to measure the rate of absorption.Absorption a t first was approximately proportional to the externalconcentrations ; as it progresses, however, it tends towards an equil-ibrium expressible by the ordinary adsorption equation. Neverthe-less, the authors wisely redrain from regarding the whole processas necessarily an adsorption.A full discussion of this interesting subject. lies outside the scopeof the present report; i t has, however, formed the subject of severalother investigations.58Plant Nutrition,It has always be’en supposed that green plants required onlyabout a dozen elements for perfect nutlrition, namely, carbh, hydro-gen, oxygen, nitrogen, phosphorus, sulphur, potassium, calcium,magnesium, sodium, and iron.P. Maz6, during the past few years,has been adding to this list, and claims as a result of his recentinvestigations 59 that traces of the following are required in addi-tion : boron, fluorine,, iodine, chlorine, silicon, aluminium, man-ganese, and zinc. On the other hand, he found no necessity fororganic substances, although some of them were helpful. Thetrace6 required must be very small, since it is a common experiencea t Rothamsted to obtain a copious and normal growth of barleyin water cultures containing the purest obtainable salts of theconventional nutritive elements.Even i f they are not essential,t%he elements in Maz6’s list appear to be beneficial in certaincircumstances, according to evidence which is steadily accumu-lating ; dhring this year, for instance, investigations have been pub-lished showing the beneficial effects, under certain conditions, ofcompounds of fluorine,gO silicon,61 aluminium,62 manganese,s35 7 Proc. Roy. SOC., 1919, [B], 90, 448 ; A., i, 240. The carrot proved verysuitable for the purpose.58 M. Williams, Ann. Bot., 1918, 32, 591 ; A., i, 59 ; W. J. V. Osterhout,J. Biol. Chem., 1918, 36, 485, 489, 557 ; A., i, 111, 112 ; F. E. Lloyd, ! I h n s -Roy. SOC. Cunuda, 1917-8, [iii], 11, 133 ; A., i, 111.5 9 Arm.Inst. Pasteur, 1919, 33, 139 ; A., i, 304.6o A. Gautier and P. Clawmann, Compt. rend., 1919, 168, 976 ; 169, 11562 J. Stoklasa and others, Biochem. Zeitsch., 1918, 91, 137.63 Idem., loc. cit. ; E. P. Deatrick, Cornell Uni?:. Agric. Exp. Sta. Mem.,A . , i, 371, 512. 61 D. S . Jennings, Soil Sci., 1919, 7, 201.1919,lg. 371 ; A., i, 428AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 185barium, and strontium.64 I n addition, traces of iodine have beenfound in plants growing under natural conditions.65Copper appears to be widely spread in the vegetable kingdom,and analyses have been made to determine how much is presentin soil. About 2 to 5 milligrams per kilo. of fine earth were foundin normal soils, but much higher amounts-200 or 250 milligramsper kilo.-in vineyard soils, where copper sprays are used.It isnot suggested that the copper is beneficial, although small amountsprobably do no harm.66 The suggestion that selenium is a definiteconstituent of animals and plants, brought forward two years ago,67has now been calleld in question.68An important development of the scientific principles ofmanuring was made some time ago by E . A. Mitscherlich in theintroduction of efficiency factors (U'irkuiigsfactoren) of manures.It is now shown69 that in the1 case of mixtures of fertilisers, thefactors remain constant so long as the constituents are withoutmutual action, but they vary as soon as interaction takes place.It has further been shown that, in the case of two nitrogenousmanures, namely, ammonium sulphate and sodium nitrate, the ratioof the respective efficiency factors is the same whether they arecalculated for corn or for straw.Between nutritive effects and toxicity the margin seems t o benarrow, and almost all of the elements essential to plant nutritionare capable of producing toxic effects under other conditions.Evenso definite and essential a plant nutrient' as a soluble phosphate isreported to be sometimes poisonous. Moreover, these effects haveno relation to the neeids of the plant; on the contrary, it has beensuggested that substances of which a plant stands most in need arecapable of exerting the greatest toxic effect. Thus, excem ofsoluble1 phosphate injures buckwheat, but, apparently not oats; yetbuckwheat is more delpendent upon phosphatic manure than oats.70Lupins afford a similar case; they greatly need lime, and yet areeasily affected adversely by it.So ammonium sulphate, a recognised and important fertiliser, is64 J.S. McHague, J . Agric. Res., 1919, 16, 183; A., i, 303.6 5 E. Winterstein, Zeitsch. physiol. Chem., 1918, 104, 54 : A . , i. 190.6 6 L. Maquenne and E. Demoussy, Compt. rend., 1919,169, 937.6 7 T. Gassmann, Zeitsch. physiol. Chem., 1916, 97, 307 ; 1917, 100, 182:6 8 R. Fritsch, ibid., 1918, 104, 59 ; A . , i, 191.6 9 Landw. Jahrb., 1918, 52, 279 ; A., i, 143.A . , 1916, i, 772 ; 1917, ii, 540.An account of these factorsis given by E. J. Russell, " Soil Conditions and Plant Growth," 3rd Edition,1917, pp. 23 et seq.T.Pfeiffer, W. Simmermacher, and M. Spangenberg, Landw. Versuchs-Stat., 1916, 89, 203186 ANNUAL REPORTS ON THE PROGRESS O F CHEMISTRY.capable under certain conditions of exerting toxic effects on theplant, and ammonium chloride is said to be even more toxic.71 I npractice, these effects are not obtained unless the soil is acid.It is, hoGever, particularly charactelristic of all the growth-pro-moting elemenh, other than the conventional nutritive elements,that their good effects are obtained only within very narrow limits,above which harmful effects are produced.This narrow margin between toxicity and growth-promotionmakes it very difficult' to ascertain with certainty the effects of someof the constituents of the plant. It is not difficult to show in watercultures the toxicity of vegetable alkaloids and related substancesto young plants.72 These are not, however, the conditions underwhich the substances act in the plant, and i t is unsafe to argue thattoxicity in water culturw proves toxicity in natural conditions.Some are known under other conditions to increase growth; thus,guanidine was found in these experiments to be toxic, yetl otherinvestigators have found it.beneficia1.73 It would, however, beequally unsafe to draw the converse deduction and, becausenutritive substances can produce toxic effects, assume that toxicsubstances can therefore exert growth-producing effects.Plant Poisons.The action is further complicated by the fact that two substancesacting together may behave very differently from eibher actingseparately .74Two practical problems arising out of toxicity have been dealtwith this year.(1) Ejfect of Lead Compounds on Vegetation.-Considerabletrouble has been experienced in the past through the refuse fromlead minels washed down on to agricultural land.J. J. Griffith75has made a careful study of the; effects produced in Cardiganshire.Leguminous crops appear t o suffer most, although all were affected,and in the case of root crops so much lead or zinc compound somet-times adhered to the roots as to cause injury to the animals eatingthem. A heavy dressing of lime afforded the best remedy.71 H. G. Stjdsrbaum, Kongl. Landtbruks-Akad. Handlingar, 191 7, 56,537 ; A., i, 60.72 Compare G.Ciamician and C. Ravenna, Atti R. Accad. Lime& 1919,[v], 28, i, 13 ; A., i, 241. For an investigation into the effect of poisonousorganic substances on germination and seedling growth, see I. Traube andH. Rosenstein, Biochem. Zeitmh., 1919, 95, 85 ; A., i, 509.73 L. Hiltner and M. Kronberger, Chem. Zentr., 1919, 90, i, 1039.74 Compare W. E. Tottingham and A. 5. Beck, Plant World, 19, 359 ; A.,7 j J. Agric. Sci., 1818, 9, 366,i , 510AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 187( 2 ) The Poisonous Effects of Coal Gas on Plants.--It is shownthat the toxicity is a positive effect, and is not due to displacementof oxygen, but is associated with the constituent to which thecharacteristic odour of coal gas is due. When this is removed, thetoxicity ceases.76 Subsequent experiments77 indicated hydrocyanicacid as the most probable agent.The Composition of Plants m a ! t h e Changes d i w i q Gmwtli.The composition of the1 plant taken as a whole alters continuouslyduring the entire period of growth, but the change, appears to beon definite lines.For this particular purpose the plant may beregarded as made up of two parts, namely, the framework and thecontained material. Each of these is tolerably constant in corn-position for a given plant, the variations being within fairly definitelimits, but the relative proportions of framework and containedmaterial vary considerably, although quite regularly, a t differentperiods of plant growth.The process of ripening and seed formation then consists in thetransfer of the cell contents (or a part thereof) t o the seed heads.Certain plants-wheat, mangolds-have1 in the past been studiedin some detail at Rothamsted, and the conclusion has been drawnthat whatever the Circumst~ances, so long as the plant growsa t all, i t will continue to make material of the same generalcharacter, and to send this into the framework or the seed heads.During the present year, the course of the growth processes in thesorghum plant has been studied in the United States,78 and theresults indicate that the plant during the1 earlier part of the seasonbuilds up its cellular structure of fibre, protein, and mineralmaterial, whilst in the later stage it' fills up these tissues withcarbohydrates-starch in the seed and sugar in the stalk.Noevidenoe was found that the leaves are deprived of carbohydratesto supply the stalk. Maturation of t<he seed heads consists almostentirely in the filling out of a fibre and protein framework withstarch.All the plant constituents, whatever their nature, are derived inthe plant from the sugar produced by photosynthesis, and thenitrates, phosphates, and other inorganic substances taken up bythe roots. Little is known of the mechanism of the changesinvolved, and thelre is still much to be learnt of chemical constitu-76 C. Wehmer, Ber. Deut. bot. Ges., 1918, 36, 140 ; A., i, 114.7' C. Wehmer, ibid., 460; A., i, 302.78 J. J. Williams, R. M. West, D. 0. Sprietstersbach, and G. E. Holm,J . Agric.Res., 1919,!18, 1188 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.tion of the substances themselves. Light is certainly essential, andthe diff erent wavelengths have different effective values.79It has been supposed, and possibly correctly, that formaldehydeis the first product of photosynthesis, but the evidence is renderedincomplete by the circumstance that formaldehyde may perhapsarise from the decomposition of chlorophyll.80The first substance detectable with certainty in the chain ofphotosynthesis is sucrosel, which is subsequently hydrolysed t odextrose and lzvulose. The next stages, however, are involved inconsiderable obscurity. It has been urged that the dextrose is usedup t o form cell contents or for purposes of respiration, whilstthe lzevulose is used for making the framework.Unfortunately,the amount of lzvulose cannot be estimated with any degree ofaccuracy,81 so that its movements cannot be followed. It has,indeed, been claimed this year that the ratio dextrose/lzevulose canbe determined; it is claimed, also, that this ratio is less than unityin the parenchyma of the leaf, but increase8 in the stem.82 If thiswere true, i t would be consistent with the1 view that dextrose1 aloneis used up for respiration, since respiration is greater in the leafthan in the stem. It does not appear, however, that the objectionsof Davis to the analytical process have really been met. Notwith-standing the unsatisfactory nature of the evidence, however, it? isstill permissible to think of the lzvulose as being concerned mainlyin building framework and the dextrose mainly in providingmaterial for cell contents and respiration.Little has been added this year t*o our knowledge of the frame-work.A paper has appeared83 on the furfuroids (related to cellu-lose) of sugar beet, but it is mainly of analytical interelst; it dealsalso with the pectoses, the supposed cementing material binding theframework together. An attempt has been made to ascertainwhether the marked effect of potassium fertiliser on grass and cerealstems is due to any stiffening of the1 framework. Microscopic es-amination, however, failed to reveal any difference in structure; y4the effect is presumably to be attributed to differences in turgidity.Much morel work has been done on the cell contents.Thedextrose generated from sucrose, is not usually stored as such, butis generally converted into starch. This, however, does not remainas starch, but is again hydrolysed, and may again be regenerated79 A. Ursprung, Ber. Deut. bot. Ges., 1918, 36, 73, 86 ; A., i, 112.so W. J. V. Osterhout, Amer. J . Bot., 1918, 5, 511 ; A., i, 597.s2 H. Colin, Compt. rend., 1919, 168, 697 ; A., i, 241.8* 0. N. Purvis, J . Agric. Sci., 1919, 9, 338.W. A. Davis, J. Agric. Sci., 1916, 7, 327.R. Gillet, Bull. Assoc. Chim. Xucr., 1918, 35, 93 ; A., ii, 302AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 189either from dextrose or from some of the other substances producedin the cell. A considerable number of sugars appear to be capableof conversion into starch in a t least certain plant cells; thus,Spirogyru in water free from carbon dioxide can form starch fromdextrose, lzvulose, galactose, raffinose, methyl alcohol, glycerol, orethyl acetate in the presence of dipotassium hydrogen phosphateand formaldehyde.It does not, however, form starch under theseconditions from lawulose, sorbose, arabinose, xylose, rhamnose, andother substances.85 Aspergillus has similar wide powers of pro-ducing starch under certain conditions.86 Of course, these sub-stances are not necessarily all found in the plantl cell, but some ofthem are widespread; carrots have been shown t o contain mannitoland dextrose, whilst green peas contain mannitol, dextrose, 1;evu-lose, and glycuronic acid.87 Mozeover, starch is not always found;in some cases, the product is inulin or the very similar inulenin.g8The carbohydrate occurring in lichens has also been studied,g9chiefly, however, with the view of obtaining a ferment'able sugar.The gums of the sorghum plant have been found to consistof complexes of galactose and pentosans with about 20 per cent.of mineral matter, chiefly calcium, magnesium, and potassium.g0Some of the plant constituents are simpler in composition thanthe sugars, and may be regarded either as degradation products ofdextrose or lzevulose, or as accompanying products in the synthesisof sucrose.A suggestedimprovement in the method of identifying this subst+ance in plantsconsists in substituting ferrous ammonium sulphat'e 91 for thepotassium salts now ofteln used.For the purpose of localising theoxalat4es, a highly concentrated solution of the ferrous salt isinjected into the plant by means of an air pump, when precipita-tion of the ferrous oxalate occurs within the cell in which the acidoccurs. Other methods suggested have involved precipitation withsaturated alcoholic sodium or potassium hydroxides, lead acetate,and barium chloride.92The presence of a salt of aconitic acid in the juice of the sugar-cane seems to be established.9s The sorghum plant! also containsOne of the commonest is oxalic acid.R 5 T. Bokorny, Biol. Zentr., 1916, 36, 385 ; A., 1918, i, 366.8 6 F. Boas, Ber. Deut. bot. GES., 1919, 37, 50 ; A., i, 508.8 7 E. Busolt, J .Landw., 1916, W, 357, 361 ; A., i, 564.88 E. Couvreur, Compt. rend. SOC. biol., 1918, 81, 40 ; A . , 1918, i, 366.89 E. Salkowski, Zeitsch. physiol. Chem., 1919, 104, 105 ; A., i, 242.J. J. Williams, R. M. West, D. 0. Sprietstersbach, and G. E. Holm,J . Agric. Res., 1919, 18, 1.91 N. Patschovsky, Ber. Deut. bot. Qes., 1918, 36, 542 ; A., i, 303.92 H. Molisch, Flora, 1918, 11-12, 60 ; A., i, 192.93 C. S. Taylor, T., 1919, 115, 886190 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.aconitic acid in addition t o malic, citric, tartaric, and oxalicacids. 94On the other hand, the simplest of all organic acids, formic acid,is of rare occurrence; its presence has been demonstrated in thehairs of stinging nettles,gj but i t is not usual elsewhere.The organic phosphorus reserve compound of plants has beenstudied in some detail in France, and its identity apparently estab-lished.I n the first place, crystalline salts were isolated, which onanalysis gave the formula C,H,,OnP,Na,,(or Na&a,),44H,0.g6Further investigation showed that three molecules o t water wereso strongly retained that they could not be removed except bydecomposing the compound; the formula was then altered toC6H,0,P6Na,,,4 7H@. 97 This indicated a hexose hexap hospha te,and examination showed the substance was really an inositol hexa-phosphate. The evidence was clinched by synthesising inositolhexaphosphate by heating inositol with phosphoric acid in thepresence of phosphoric oxide at 120-130° for three hours, andthen showing that the double sodium calcium salt had identicalcrystallographic propert-ies with that prepared from the naturallyoccurring substance.98Besides the sugars and the phosphorus compounds, there arelarge numbers of other plant constituents, some of which arechemically simple and others are not.There is a steady increasein chemical knowledge of the complex plant substances. Fortu-nately, the investigations of Willstatter on chlorophyll arecontinuing.99Another group of constituents at least as complex as chlorophyllare the chromatins. Investigation of them substances is difficult,and little has been added to our knowledge during the year. It isnow stated that the substance previously described by Dangeard asmetachromatin in higher plants is not comparable with the meta-chromatin of fungi, but is a phenolic compound capable of beingconverted into anthocyanin.1 A large body of constituents is,~34 J.J. Williams, R. M. West, D. 0. Sprietstersbach, and G . E. Holm,J. Agric. Res., 1919, 18, 1.O 5 L. Dobbin, Proc. Boy. SOC. Edin., 1918-19, 39, 137 ; A., i, 614.96 S. Posternak, Compt. rend., 1919, 168, 1216 ; A., i, 426.9 7 S. Posternak, ibid., 169, 37 ; A., i, 426 ; Society of Chemical Industry in98 S. Posternak, ibid., 138 ; A., i, 433.9 9 R. Willstatter, 0. Schuppli, and E. W. Mayer. Annalen, 1919, 418, 121 ;A., i, 448.For a discussion of the bearing of this work on the mechanism of assimilationsee R. Willstatter and A. Stoll ( B e y . , 1917, 50, 1777 ; A., 1918, i, 207) andK.Schaum (Ber., 1918, 51, 1372 ; A., i, 111).Basle, Brit. Pat. 130456 ; A., i, 504.1 A. Guilliermond, Compt. wnd., 1918, 166, 958 : A., 1918, i , 366AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 191however, proving more amenable to chemical treatment. Thetannins, wh'ich are very widely spread, have been studied by EmilFischer,2 and their relation to the mellowing of fruits has beediscussed by C. Griebel and A. Schafer.3Some new or little known glucosides have also been described,some occurring in the cotton plant4 and some in the orchid.5 Thesaponin occurring in lucerne has also been studied; its formula isgiven as C,,H,,O,,N; it is abnormal in that it contains nitrogenand does not haemolyse blood. Like other saponins, it poisons fish,but i t is said to act by preventing the diffusion of air into the water,and not in virtue of any special toxic property.6 Other saponinsinvestigated have been from the root of Platycodon grandi-@0rz~.m.7The substance indican is of special interest, because of its greattechnical importance in connexion with indigo.Davis claims thatthere is a marked need for phosphatic fertilisers in order to securea proper yield under Indian conditions.8 A new method of pre-paring indican from the indigo plant has also been described, andis said to be more rapid and complete than other methods.9From the agricultural point of view, the nitrogen compoundsare often more interesting than the others. It has been customaryto identify these by hydrolysis with hydrochloric acid and ex-amination of the products by the Van Slyke method.Whilst themethod has advantages, there is considerable evidencel that it breaksdown in particular mes.10The only safe plan is to isolate the protein and study it in aspure a state as possible. It is known that the protein is formed insome way from sugar and an inorganic nitrate, and an attempt1*has been made to express the course of the reaction. It is assumedthat the sugar reacts with nitrogen, phosphorus, and sulphurderived from inorganic salts to yield proteins; the bases of the salts2 E. Fischer and M. Bergmann, Ber., 1918, 51, 1760 ; 1919, 52, [B], 829 ;A . , i, 87, 278.Zeitsch. Nahr.-Genussm., 1919, 37, 97 ; A., i, 427.A. Viehoever, L. H. Chernoff, and C.0. Johns, J . Agric. Res., 1918, 13,Also E. E. Stanford and A. Viehoever, ibid., 13, 419 ;5 E. Bourquelot and M. Bridel, Compt. rend., 1919, 188, 701; A.,345 ; A . , 1918, i, 367.A., 1918, i, 367.i, 243.G. A. Jacobson, J . Amer. Chem. SOC., 1919, 41, 640; A . , i, 375.7 H. Oshika, Kyoto Igaku Zasshi, 1918, 15, 56 ; A., i, 427.8 Agric. J . India, 1919, 14, 21.B. M. Amin, Agric. Res. Inst. Pusa, Indigo PubZ., No. 5 ; A., i, 283.10 J. F. Brewster and C. L. Alsberg, J . Biol. Chern., 1919, 37, 367; A . ,l1 A. Meyer, Ber. Deut. bot. Ges., 1918, 36, 508 ; A., i, 210.i, 239192 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.are thereby liberated and neutralised by the organic acid producedin the leaves; the process is formulated thus:27C,H@, + 24Ca(NO,), + CaSO, + 25H,C20, =C162H262053N48S f 25CaC@, f 2010 -t 56H20.The interest of the agricultural chelmist in the constituents ofplants lies in their feeding value to meln and animals but especiallyanimals, and this depends on two types of compounds, the nutrients,of which large quantities are required, and the vitamines, neededonly in small amounts.Water-soluble vitamine has been found inthe bulb of the onion, the root of the turnip,l2 the fruit of thetomato, and the leaves, stem, and root of the beet. I n the case ofclover, lucerne, and timothy, the larger amount of vitsmine wasfound in the immature plant, which may help to account for thesuperior feeding value of the younger over the older grass.The antiscorbutic factor present in green peas is lost on drying,and hence dried peas and lentils are not as valuable in a dietaryas they might be.H. Chick and E. M. Delf have shown,13 how-ever, that the factor increases five or six times in amount when t'hepeas are soaked for twenty-four hours and then allowed to germinatefor forty-eight hours; the amount then becomes equal to that foundin green peas and potatoes, and greater than that in carrots orbeetroots.I n the case of wheat grain, the water-soluble vitamine appearsto be localised in the endosperm, but it is not uniformly distributedthere.The nutritive value of the constituents is more properly dealtwith by the physiologist than the agriculturist. Reference may bemade, however, to the extensive paper, just quoted, by Osborne andMendel on the nutritive value of the wheat kernel and its millingproducts .None could be found in t,he pure embryo.14The Mechmtism of the Reactions in t h e Plant.Although very little is known of the course of t<he reactions inthe plant, some knowledge has been gained of the conditions deter-mining them.I n the first place, the so-called mineral elements-potassium,calcium, phosphorus, etc.-are essential, although this fact is oftenoverlooked in attempts at reconstructing the plant processes.l2 T.B. Osborne and L. B. Mendel, J. Biol. Chem., 1919, 39, 29 ; A., i, 510.l3 Biochem. J . , 1919, 13, 199.l4 T. B. Osborne and L. B. Mendel, J. Biol. Chem., 1919, 37, 557 ; A . ,i, 298AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY.193Analyses of the plant ash are frequently niade,lj and, whilstl thefigures are not at, present, illuminating, they will presumably someday find an interpretation. Oiie instance only need be quoted,the case of the ash of the spinach plant grown under con-ditions of high manuring.16 The constituents fall into1 two groups:those present in quantity but varying little, whatever thef ertilisers added t o the soil-lime, magnesia, manganese, alumina,iron, phosphorus, and sulphur-and those that show great fluctua-tions in t,he quantity present, including silica, potash, and soda.The variations sometimes, but, not always, are in the same directionas those1 in the soil.The ash constituents sometimes precipitate out' as the result ofinteractions in the plantq.The second important consideration is that the processes arecarried on in the main by enzymes.A little reflection will showthat this is necessary, since the ordinary means of expeditinga reaction by rise of temperature or of concentrationare inapplicable in the growing plant; a catalyst is thereforeessential.A discussion of the enzymes of plants mould be outside the scopeof this Report; it is possible only t o indicate some of the workcarried out' during the year. Undoubtedly the paper of mostgeneral interest is one describing an attempt by Willstatter andStoll to work out the constitution of peroxydase, using the materialobtained from thel horse1 radish. They endeavoured to prepare purespecimens of the enzyme1 so as t o find out whether it, is a singlesubstance or a system of co-operating substances, whether a metalis an integral part of the enzyme, and what atomic groups areresponsible for enzymic activity.18 The enzyme does not, appear tobe hopelessly complex in structure; i t seems t o consist chiefly of anitrogenous glucoside containing a pentose arid a moleculaiquantity of another sugar, probably a hexose.Mineral matter isalso present, but iron, a t any rate, scarcely seems necessary f o r theeffective action of the enzymel.Other papers of interest include1 one on the oxydases of sugar-l5 See, for example, L. Leroux and D. Leroux, Ann. Chim. anal., 1919,[ii], 1, 2 0 7 ; A., i, 563; A. Lacroix, Compt. rend., 1918, 166, 1013; A., 1918,i, 366.l6 R.H. True, 0. F. Black, and J. W. Kelly, J . Agric. Res., 1919,16, 15.l7 A. Wichmann, Proc. K . Akad. Wetensch. Amsterdam, 1919, 21, 968 ;A., i, 564 (phosphates) ; also H. Molisch, Uer. Deut. hot. Gcs., 1918, 36, 277,474 ; A., i, 113, 242 (silica).R. Willstatter and A. Stoll, AnnuZen, 1915, 416, 21 ; A., 1915,i, 555.REP.-VOL. XVI. 194 ANNUAL REPORTS ON THE PROGRESS OP CHEMISTRY.cane,19 of the pear and the potato,Z0 of seeds,21 and of fresh anddried vegetables22An attempt has been made to express the delgradation of starchunder the action of diastase.23The vegetable proteases have also belen investigated, and theproteinoclastic and peptoclastic action of leaves measured a tdifferent periods of growth.24One of the most characteristio reactions in the plant is tshe pro-duction of aminocacids by the interaction of sugar and nitrate.Presumably reduction takes place at some stage, and 0.Baudisch25has attempted to reproduce the reaction in the laboratory; he hasworked out a reduction which resembles the natural process in thatan iron salt and oxygen both take part. B. Moore has also inveeti-gated the early stages in the synthesis of nitrogen compounds.26Feeding Stuffs.Several investigations have been made on the feeding value t oanimals of green crops. Green maize has been studied to findout the cause of the loss of sugar which is known to occur soonafter the plant is cut. It, is suggested27 that this loss is only inpart due t o respira,tion; most of it is attributed to condensationto form more complex substances, especially starch.It is knownthat the sugar content of green sweet maize falls off rapidly whenthe plant is cut.Certain green crops occasionally have harmful, and even fatal,effects on cattle. C. T. Dowel128 records a case in Oklahoma wheresorghum cut when 75 cm. high, a t a time of great drought,, killedno fewer than ten out of twelve cattle within an hour. Investiga-tion showed this to be a case of cyanogenesis. Itl was shown, holw-ever, that dried sorghum and mature sorghum are both safe feed-ing stuffs; if in a less mature sample there is any doubt about thepresence of the cyanogenetic glucoside, the ill-eff ects can be obviatedby giving some concentrated fe'eding stuffs. The explanation sug-l9 R.Narain, Agric. J. India, 1918, 47; A., i, 114.2o M. W. Onslow, Biochem. J., 1919, 13, 1 ; A., i, 361.21 W. Crocker and G. T. Harrington, J. Agric. Res., 1918, 15, 137; A.,22 K. G. Falk, G. McGuire, and E. Blount, J. Biol. Chem., 1919, 38, 229 ;23 M. Samec, Koll. Chem. Beihcfte, 1919, 10, 289 ; A., i, 472.24 E. A. Fisher, Biochem. J., 1919, 13, 124; A., i, 464.25 Ber., 1919, 52, [B], 35, 4 0 ; A., i, 237, 238.2 G PYOC. Roy. Soc., 1918, [B], 90, 158; A., 1918, i, 365.27 C. 0. Appleman and J. M. Arthur, J. Agric. Re$., 1919, 17, 137.33 llhid., 16. 175.i, 110.A., i, 426AGRICULTURAL CHEMISTRY AND VEGETABLE PHYSIOLOGY. 195gested is that the dextrose and maltose produced by salivary diges-tion prevent liberation of the hydrocyanio acid.A common method of preserving green food over the winter isto cut it up and store it under amrobic conditions in a large vatcalled a silo; the product is known as silage.The sugars rapidlychange to acetic and other fatty acids, and a certain amount ofhydrolysis of the proteins takes place, but after the first rapidreactions there is little subsequent change, and the material keepsall through the winter. More products are periodically found inthe silagel; this year, acetylmethylcarbinol has been detected insorghum silage.29 Analyses have been made of the mixture occur-ring in ensiled cabbage, or sauerkraut .30Agricultural chemists have long tried to solve the problem ofevaluat'ing the fibre in feeding stuffs, the conventional method ofsuccessive acid and alkali treatment suffering from certain dis-advantages ; in particular, it dissolves some material which theanimal cannot digest. A new method, based on the absorption ofchlorine by the fibre, is claimed to give satisfactory results.31Another analytical problem as yet unsolved is to discriminatebetween one nitrogen compound and another in a feeding stuff.The Van Slyke method has obvious advantages, although, as alreadypointed out, it is liable to fail in dealing with plant pro-ducb. Two improvements have been effected32: (1) p r eliminary extraction, first with ether and thea with cold absolutealcohol, to remove non-protein substances that interfere with thereaction, and (2) reduction in the amount of humin nitrogen formedduring the reaction. It is claimed that these improvements putthe method on a much more satisfactory basis.The hydrogen electrode has been used for determining the acidityand the titratlable nitrogen in wheat. The process is not quitesimple, as the substances in the solution formed when wheat is ex-tracted with water are not ionised until an alkali has beenadded.3329 W. G. Friedemann and C. T. Dowell, J . I d . Eng. Chem., 1919, 11, 129 ;30 V. E. Nelson and A. J. Beck, J . Amer. Chem. Soc., 1918, 40, 1001 ; A.,31 P. Waentig and W. Gierisch, Zeitsch. physiol. Chem., 1918, 103, 87;32 H. C. Eckstein and H. S. Grindley, J . Biol. Chem., 1919, 37, 373; A.,33 C. 0. Swanson and E. L. Tague, J . Agric. Res., 1919, 16, 1 ; A., ii, 176.A., i, 244.1918, i, 364.A., ii, 173.ii, 204.a 196 ANNUAL REPORTS ON THE PROGRESS Ol? CHEMISTRY.Insecticides and Fungicides.Investigation has been made into the composition of Burgundy~ixture,34 a well-known and very useful copper spray, and of therulphur washes.35 I n addition, there has been some work on theuse of formaldehyde vapour for seed disinfection,36 and of chlor-picrin37 for the killing of insects. The investigation of thechanges in composition undergonet by arsenical fluids in cattle-dipping baths has led H. H. Green in South Africa t o the interest-ing discovery of certain bacteria capable of oxidising arsenites toarsenates, and of others capable of reducing arsenates t o arsenites.38E. J. RUSSELL.34 R. L. Mond and C. Heberlein, T., 1919, 115, 908.35 J. V. Eyre, E. S. Salmon, and L. K. Wormald, J . Agric. Sci., 1919,36 C. C. Thomas, J . Agric. Rcs., 1919, 17, 33.37 G. Bertrand, Brocq-Rousseu, and Dassonville, Compt. rend., 1919, 169,38 Union of S. Africa, 5th and 6th Reports, Veterinary Research, 1919, 593.9, 283.1059, 1428