70 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



Thickening 1 of the Cell-walls in the Leaf-stalk of Aralia.* — Big. 

 P. Pichi describes the mode of thickening of the walls of the liber-cells 

 in the phloem of the fibrovascuhir bundles in tho leaf-stalk of Aralia 

 trifoliata. In the early stages the thickening takes place chiefly in the 

 angles, producing a very strong resemblance to collenchymatous tissue. 

 Later, very delicate layers of cellulose are formed within each cell, 

 which become rapidly lignificd. Sig. Pichi considers it probable that 

 during the early stages, the thickening takes place chiefly by intussus- 

 ception, during the later stages by apposition. 



C2) Other Cell-contents (including- Secretions). 



Starch- and Chlorophyll-grains.— M. E. Belzungf has made a series 

 of observations on the morphological and physiological relationship 

 between starch and chlorophyll, which has led him to conclusions 

 differing in several respects from those generally accepted. 



In investigating the origin of starch-grains, especially in the ovules 

 of Leguminosae, M. Belzung finds that, during the formation of the 

 ovule, the embryo, the transitory endosperm, and the integuments, in fact, 

 the entire seed, is the seat of a new-formation of starch unconnected with 

 the previous existence of any leucite or starch-generator ; the grains of 

 starch are formed free in the protoplasm by simple crystallization of the 

 amylaceous matter dissolved in the cell. This is true both of accumula- 

 tions of reserve-starch and of such as is at once used up in the growth 

 of the plant. The theory of Schimper that the leucites are the sole 

 generators of starch is further in opposition to the fact that even when 

 a starch-grain is apparently formed within a leucite, it will continue to 

 grow long after the latter has disappeared. During the development of 

 the transitory starch-grains they undergo a curious metamorphosis. A 

 portion of their substance is consumed, and is used for the production of 

 albuminoids, while the other portion is partially hydrated, and takes 

 the form of a granular skeleton of the same shape, which is coloured 

 yellow or reddish-yellow by iodine reagents. These skeletons are 

 analogous to those obtained by the action of saliva or of dilute acids on 

 the starch-grains in the living plant. They are composed of amylo- 

 dextrin, and the author proposes for them the term amylites. They 

 were found in ripe seeds and in the axis and cotyledons of the lupin. 

 The transitory starch which appears during the germination of seeds 

 is deposited in these amylites, and is formed at their expense. This 

 transitory formation of starch has no connection with the actual assimila- 

 tion of carbon. 



The normal function of transitory starch-grains is to form grains of 

 chlorophyll. The chloramylite is the substratum of the future chloro- 

 phyll-grain, and the cell-protoplasm takes no part in its formation. 

 Chlorophyll-grains with an amylaceous origin must be carefully distin- 

 guished from those with a protoplasmic origin. During the early period 

 of germination chloramylites only are to be found in the stem, to the 

 exclusion of chloroleucites. Eeserve-starch-grains exhibit the same 

 phenomena ; and they occur in all plants except Fungi, which contain 

 transitory, but no reserve-starch. 



* Atti Soc. Tosc. Sci. Nat., viii. (1887) pp. 455-8 (1 pi.). 



t Ann. Sci. Nat.— Bot., v. (1887) pp. 179-310 (4 pis.). Cf. this Journal, 1887, 

 V. 423. 



