1917] AGRICULTURAL BOTAJSTY. 633 



factor then overcoming that of the enzym. Rise of temperature increases 

 markedly the rate of assimilation in such leaves, while in leaves poor in chloro- 

 phyll that process is but little increased between 15 and 30° C, the enzym 

 supposedly exerting its full effect in that case. The enzym, it is thought, may 

 facilitate the decomposition of an intermediate compound of chlorophyll and 

 carbon dioxid with liberation of oxygen. 



Studies on the chemical transformations in the leaf of Diospyros kaki 

 during the vegetative period and on its autumnal coloration, A. Pakeozzani 

 (Ann. R. Staz. Sper. Agrum. e Frutticol. Acireale, S {1915), pp. 43-90). — Con- 

 cluding this partial report of a study of D. kaki as herein detailed, the author 

 states that the facts as noted do not corroborate the view of a return of certain 

 substances to the trunk before the fall of the leaves, but rather favor the view 

 that the diminution of certain substances in the leaf at that time is caused 

 by the action of water on the leaf and that the diminution of such substances 

 as hydrocarbons may be attributed to oxidation. The autumnal red in leaves 

 is thought to be due to the formation of a substance of glucosid nature which 

 is altered in consequence of hydrolysis following oxidation. 



On the assimilation of iron by plants, M. I. Sidobin (Jz Rezul't. Yeget. 

 Opytov Lab. Rahot {Rec. Trav. Lab. Agron.), Moskov. Selsk. Khoz. Inst., 10 

 (1914), PP- 241-257, pi. 1, figs. 5). — Investigations carried on in sand and water 

 cultures in 1914, but not published until 1916, are held to show that the occur- 

 rence of chlorosis in plants grown in nutrient solutions with an excess of car- 

 bonates, especially calcium carbonate, depends on the alkalinity of the 

 solution. 



Alkalinity of itself is not the cause of chlorosis, but it is due to inaccessibility 

 or lack of assimilation of iron under alkaline conditions. The same results 

 may occur in nutrient solutions under conditions of physiological alkalinity. 

 The ability of iron to form nearly insoluble compounds with phosphoric acid is 

 often the cause of the poor assimilation of iron. The lack of chlorophyll in 

 plants that have been grown without injury is partly analogous to chlorosis 

 due to the lack of iron. It is claimed that iron has the property of being 

 strictly localized in plant tissues, and this was conclusively shown in experi- 

 ments with maize, in which the roots of plants were divided and grown in 

 different solutions, one containing, the other lacking, iron. 



Changes in the specific gravity of starches and dry substance of potatoes 

 during the resting period, L. Szell (Kis&rlet. Kozlem., 18 (1915), No. 5-6, pp. 

 1020-1029). — A study was made of two potato varieties kept in the cellar and 

 also in heaps in the open air. It was found that the specific gravity of 

 starches and dry substance increased in the potatoes kept in the cellar but not 

 in those kept in the open. The conclusion is reached that it pays to winter 

 potatoes in good, airy cellars. 



Changes in the chemical composition of rye under the influence of species 

 of Fusarium, A. Pomaskii (Soobshch. Bi^ro Chastn. Rast., [Petrograd], 3 

 (1916), No. 1, pp. 32). — Analyses and experiments made with F. roseum and 

 F. subulatum showed that their presence on rye caused a decrease in dry 

 substance, chiefly starch and proteids, the percentage of which fell in ten 

 days to 67.3 per cent and in two months to 25.1 per cent. The amount of 

 starch decomposed in one month was from 61 to 80 per cent, in two months, 

 86.5 to 89.5 per cent. The total quantity of nitrogen in cultures of F. roseum 

 decreased about 5 per cent in the first ten days, and in a month the amount of 

 nitrogen in a culture of F. subulatum had diminished by 2.7 per cent. The 

 decrease of nitrogen with both species amounted to from 12 to 16 per cent 

 in two months. Both species of Fusarium were found to be able to decompose 

 starch and protein. The products of the decomposition of protein were albu- 



