ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 983 



the cotyledons completely fill the seed-coat, there is no trace of the 

 aleurone-grains, the cells contain a conspicuous nucleus slung in the 

 centre by thick protoplasmic bridles, or sometimes lying in the parietal 

 protoplasm. If sections of the cotyledons be examined when the seeds 

 begin to swell, the cells are seen to contain small spherical or oval 

 bodies, partly or wholly projecting from the granular protoplasm, 

 whether the parietal layer or that surrounding the nucleus, or forming 

 the connecting strands. These bodies are the rudimentary aleurone- 

 grains ; they increase in size and number and soon fill up the vacuole. 

 The grains, therefore, are evidently actually secreted by and in the 

 protoplasm itself. Solid organic constituents were repeatedly sought 

 for, but without success. 



Occurrence of Starch in the Onion.* — Mr. A. B. Eendle states that 

 the leaves of the onion are known to be somewhat exceptional in that 

 they do not form starch in the process of assimilation ; glucose, 

 which is present in large quantities in the mesophyll-cells, apparently 

 taking its place. From the papers of Bohm, Schimper, A. Meyer, and 

 others, it would appear that the green leaf of the onion does not form 

 starch at all. From the author's experiments, however, it is evident 

 that the onion is rather to be considered as an extreme instance of a 

 plant like Euphorbia Lathyris, where the starch is present almost 

 exclusively near the vascular bundle and at the base of the leaves ; since, 

 at any rate in seedlings, starch occurs nnder natural conditions in the 

 same position as in this plant. 



Formation of Starch in the Chlorophyll-grains.t— Sig. G. Bellucci 

 finds, by experiment on a number of plants, that, during the day starch 

 and glucose accumulate in the plant, especially the latter. By night 

 the starch disappears almost entirely from the leaves, while the quantity 

 of glucose remains nearly unchanged, the loss from metabolism being 

 compensated by constant transformation of starch into sugar. In the 

 grape-vine, if the fruit is cut off, the amount of glucose in the leaves 

 increases, not being used up in other parts. Experiments with cut 

 portions of plants afford no guide for what takes place in the living 

 plant. 



Reserve-substances in Evergreen Leaves.f — Herr E. Schulz has 

 investigated the mode of formation and distribution of the reserve- 

 substances, especially tannin, in the leaves of a number of evergreen 

 trees and shrubs, both Angiosperms and Gymnosperms. The following 

 are the more important results : — 



Sachs's view that evergreen leaves serve during the period of rest as 

 receptacles for reserve-materials, and Haberlandt's, that the assimilating 

 tissue of evergreen leaves performs this function, are true for Gymno- 

 sperms and most Dicotyledons. This accumulation of reserve-substances 

 cannot, however, be demonstrated in the case of Monocotyledons and 

 some Dicotyledons. The author was unable to confirm Zimmermann's 

 statement that the parenchymatous cells which accompany the transfusion- 

 tissue in Coniferas, and the sheath which surrounds them, contain starch 

 in the dormant period. Haberlandt's assertion that the starch disappears 

 from evergreen leaves in October, and makes its appearance again in 



* Ann. of Bot., ii. (1888) pp. 225-7. 



t Staz. sperim. agrarie ital., xiv. (1888) pp. 77-85. See Bot. Centralbl., xxxv. 

 (1888) p. 231. X Flora, Ixxi. (1888) pp. 223-41, 248-58 (1 pi.). 



