26 Chemistry of Vegetable Physiology and Agriculture. containing Chromo- The Separation of Oxygen by Cells phyll. By T. W. ESGELNANX (Iy?iiger’.s Archiz~, 1894,57, $75-386).- I n these researches, the bacterial method mas employed, and trhe results, which are illustrateti by coloured figures, were as follows. Green plant cells gim off oxygen in the light, the amonnt within wide h i t s varl-ing with the illumination. The bacteria used need free oxygen for their inovernents, and within wide limits the amount of movement varies with the amount of oxygen. In cells with cliromophyll granules, this test shows that the granules are the source of thc osjgcn ; colourless protoplasm, cell membrane, and nucleus are not. Red light, which is that most absorbed by chloro- phyll, leads to the greatest development of oxygen.The green pig- ment is not itself capable of so acting; it must be present in connection with the living stroine of the chlorophyll granule. Other chromophylls act similarly. W. D. H. Hydrogen Peroxide in Green Plants. By A. B.icIr (COW@. yew?., 1894, 119, e86-288) .-The author has investigated the applicability of the various reagents for hydrogen peroxide to the detection of this substance in the leaves of green plants or the extract from them. Tetramethylparaphenjleiied iamine is coloured by calcium chloride and by g l p r o l owing to their absorption of oxjgen, and is also affected by nitrous acid; on this account the results obtained are always open to question. Tincture of guaiacum in presence of diastase is difficult to use, and the results are uncertain.Potassium iodide and starch in presence of ferroixs sulphate is affected by any unsaturated substances that can absorb iodine, and such substances are always present in the leaf extract. Titanic oxide dissolved in sulphuric acid gives, with tannin, the same coloration as with hydrogen per- oxide, arid tannin is always present in leaf extract. Uranium acetate is precipitated by albumin and by tannin, and the tnrbidity does not completely disappear on adding acetic acid. Potassium dichromate and ether is never very sensitive, and is much less sensitive in pre- sence of a solntion of tannin or an extract of leaves. It follows that none of the orciinary reagents for hydrogen peroxide yield satisfactory results when applied t o leaves or an extract of leaves.C. H. B. Formation of Substance in Sea, Algae. By A. HANSEN (Bid. Ceiztr., 1894, 23, 544-545 ; from Nutww. Ktmdsch., 1593, 73.).--The Phceoph ycea (especially Dictyoqna) do not produce starch but fat. The substance found in the cells of the inner cell-layer of the thin sprouts, which Berthold supposed to be albuminous. gives the micro- chemical reaction of fat. The cells serve as a storing place for the f a t which is produced in the assirdative tissues. Fat was also found in Taoizin atonzai.in and in IIaZyseris p7ypodioides, wliilst oil could beVEQETABLE PHYSIOLOGY AND AQRICULTURE. 27 detected in Asperococczrs hydroclath~zu and in Cystoseira. The pro- duction of substance in the Floridcce seems to be morc complicated. The cells of the assimilative tissues of Choizdriopsis ccprzclesceiis con- tain % globular substmice which reflects light in a peculiar manner, and, according to Kny, gives rise to the iridescence of this plant.Inasmuch as no oil or starch, be., could bc found in the cells, this substance i s probably a food. It swells up in water, dissolves in alcohol, and becomes da& (but not black) when treated with osmic acid, and brown when treated with iodine. A starch-like substance was only found in GmciZuria (a siiiall species of Floridece). An examination of the dyes of sea algze indicated that the red colour of the FloriJece is the albumin compound of a dye, like hIcmo- globin. The green colour of the FZoritSect, can be separated into cz yellow dye, and a green dye, probably ordinary chlorophyll. Many of tho Floritlecc are almost green, and these grow near the surfscc ; the deeper-growing ones increase in redness the deeper tliey occur.It is assumed that the red dye absorbs the dissolced oxygen of the mnter. N. H. It. Physiological Meaning of the Cyanic Colouring Matters. By L. KXY (Bied. Cent,.., 1894, 23, 546-547 ; from Natiirw. Btr~izclsch., 1893, 6'LO).-According to Kerner, the object of the cyanic colouring matters is to protect the chlorophyll in young organs by shading from the light, or, on the underside of leaves, to convert light rays into heat rays. In stems and leaf veins, Pick and Kerner connect their presence as screens with the iiiovement and decomposition of plastic substances. An alcoholic chlorophyll solution was exposed to light which first passed throiigh a red extract of Beta zulgaris (zav.rzcbra), and through a white extract of B. vzilgas.is (var. mpa) respectively. I t was found that the red solution did delay the decomposition of the chlorophyll, as the solution kept under the white extract was first changed. As regards the transformation of light r a p into heat by the colour- ing matters, it was found that when the leaves of beech, hazel, bar- berry, maple, cabbage, Dracnena f e w e a , Caitna indicn, and beet, were exposed to sun light previously passed through alum solution, the temperature of the YesseIs contaiuing red leaves became higher than in the case of green or white leaves. The greatest difference was 4'. When the direct light was cut off, the vessels containing the red leaves cooled first, the temperature of both vessels becoming about eqcal in 10 or 20 minutes. N.H. 31. Presence of Several Distinct Chlorophylls in the Same Vege- table Species. By A. ~ A R D (Compt. rend., 1894,119, 289-2'31). See this vol., i, 66. Calcium Citrate in Plants. By C. WEHJIER (Ann. Agwa., 1894,20, 391 ; from Ber. deut. bot. Ges., 1893, 333).-After calling attention to the very sparing solubility of calcium citrate in water, the author suggests that some of the crystalline deposits in plants (such as the28 ABSTRAOTS OF CHEMICAL PAPERS. raphides and some sphero-crystals), hitherto supposed to be cal- cium oxalate, may be citrate. Citric acid has a rale in respiration ; i t is by no means demonstrated that all the carbonic anhydride liberated during respiration is produced from albumin, and i t seems more likely that acids containing large amounts of oxygen may under- go complete combustion.Nutrition of Plants by Humus and Organic Substances. By E. B R ~ A L (Ann. Ayron., 1894, 20, 353--370).-A large portion of the paper is a re'sume' of experiments hitherto made on vegetation, without any organic matter, with humus substances and stable man- ure, water culture experiments with mineral salts and calcium humate, and experiments on the direct absorption of organic matter by plants. Although there was no doubt as to the beneficial effect of humus 011 plants, there was no evidence to show that the humus was directly absorbed, excluding the possibility of the intervention of lower organisms.In the first experiment now described, a tuft of grass (Poa anma) was taken from the soil, the roots cut off and fresh roots obtained by water culture. The tnft was next divided into two equal parts, the one placed in a dish of potassium humah (carefully prepared from soil), whilst the roots of the other portion, after clitting off the tops, were placed in a similar vessel containing the same amount of potas- sium humate solution. I n two or three days the roots of the whole plants entirely removed the potassium humate, the bottom of the dish teing perfectly white ; whilst the roots alone in the other dish seemed to have had no effect, the liqnid being as dark as a t first. On filtering the two liquids and estimating the carbon, the liquid which had con- tained the entire plants gave only 0*005 gram of carbonic anhydride, tlie other 0.025 gram.The potassium humate, had, therefore, been directly absorbed by the plants. The roots of Poa left in water ovcr a filter paper covered with potassium humate, adhered tightly to the paper, leaving marks, when removed, resem- blizig those which Snchs obtained by the corroding action of roots on marble. When trefoil plants and roots respectively were kept in solu- tions of sodium humate, the results obtained were similar to those with You and potassium humate. Finally, an experiment is described in which the roots of entire plants (You annzca), suspended in a solution containing sugar, com- pletely absorbed the sugar, whilst the roots alone of similar plants did not. In this case, again, the absorption must have been direct, without the intervention of lower organisms.N. H. &I. Other experiments are described cor;firming this result. N. H. M. Agricultural Value of Various Natural Phcsphates. By G. PATUHEL (Anw Agron., 1894,20,316-348) .--The natural phosphates of various places, especially those of Brittany, have various commercial values attributed to them which do not always correspond with the eflect produced by them on crops. The object of the present investiga- tiun was t o ascertain why the phosphate of the green-stone (Boulon- nais) are preferred to those of the Somme.VEQETABLE PHYSIOLOQY AND AQRIOULTURE. 29 The employment of ammonium citrate or oxalate for the estimation of available phosphoric acid, does not give trustworthy results when applied t o natural phosphates.Weak acids, such as acetic acid (DehBrain) or citric acid (Dyer), seem much more likely to gire good results, as their action is comparable with both that of the acid of the soil and of root sap. The results of the author’s experiments on the action of dilute citric acid on the two phosphates in question, show, in the first place, that a 10 per cent. solution of citric acid dissolved very much more than a 1 per cent. solution. The amount of phosphates dis- solved depended, however, on the amount of lime present when the results obtained with acid solution of a particular strength are com- pared. Thus, a Somme phosphate (with 24 per cent. total phosphoric acid and 13.8 per cent. of lime) gives up a smaller percentage of phosphoric acid than the Boiilonnais phosphate (with 19 per cent. of total phosphoric acid and 7.6 per cent.of lime). Calcium carbonate seems to have a special retarding effect on the solvent action of the acid. This is not due merely to the neutralisation of the acid by the lime, as the differences in the amounts dissolved from the two phos- phates were almost the same, whether 10, 5, 2, or 1 per cent. solu- tions were employed. I n the case of a chalky phosphate (phosphoric acid 16.24, lime 57.2 per cent.), practically no phosphoric acid (less than 1 per cent.) was dissolved. In this case, the 1 and 2 per cent. acid sollitions hardly showed an acid reaction after 24 hours. The next experiments were made with acetic acid. Except that acetic acid is it much feebler solvent for the phosphate than is citric acid, tho results were similar. The effect of carbonic nnbydride alone, in conjunction with citric acid, and with acetic acid respectively, was also examined.Carbonic anhydride alone dissolved very little of the phosphate, and did not have any marked effect when employed with acetic or citric acid. In a subsequent experiment, however, in which the phosphates had been kept for some time in water containing carbonic anhydride, then extracted with 10 per cent. acetic acid solution, a considerably higher percentage of phosphoric acid was dissolved, doubtless because a part of the lime had been dissolved by the carbonic anhydride. The results of the experiments showing t>hat the Boulonnais phos- phate was more soluble in citric acid than the Somme phosphate is in accordance with the known effect of the two manures in agri- cnl tu re. I n estimating the value of mineral phosphates, the quantity of lime 8s well as that of phosphoric acid (soluble in dilute acid) should be determined. I n the case of such phosphates as those of the Somme, it would probably be worth while to remove part of the lime before applying them to the land. This is, however, a point to he decided by direct field experiments. N. H. M.