ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 443 



cytoplasm, the nucleus and chromatophores, cilia, and " eye-spot," the 

 " bacteroids " and ciliated bodies of tbe Cbaracea3, protein-grains and 

 crystalloids, tbe starcb-grains and nearly related structures, sucb as tbe 

 starcb of tbe Khodophyceaa and Plueopbycea?, amylon and cellulin, tbe 

 various otber cell-contents, cell-sap, and cell-wall. Finally, tbe various 

 phenomena of tbe pbysiology of tbe cell are discussed. 



C2) Other Cell-contents (including Secretions). 



Formation of Aleurone-grains.* — According to observations of Herr 

 J. H. Wakker, aleurone-grains are not, as bas been generally stated, 

 dried masses of protoplasm ; but, at least in many cases, are vacuoles 

 filled witb soluble albuminoids ; and bence tbe crystals, crystalloids, 

 and globoids found in tbem are not formed in tbe protoplasm, but within 

 tbe cell-sap. Tbe investigations were chiefly made on a large number of 

 seeds. In tbe process of germination the aleurone-grains first become 

 vacuoles by tbe absorption of water, tbe albumen then gradually dis- 

 appears from them ; the vacuoles usually become smaller, and finally 

 the globoids and crystalloids are dissolved. The crystalloids of Der- 

 bcsia Lamourouxii were also found to have their origin in the cell-sap. 



Elaioplast.j — Under this term Herr J. H. Wakker describes nearly 

 globular strongly refringent yellow bodies which he finds, in addition to 

 the colourless amyloplasts, in epidermal cells of the leaves of Vanilla 

 planifolia. They exceed in size both the amyloplasts and the nuclei, 

 having a diameter of 8-10 //, in the half-formed leaf. Treatment witb 

 a 10 per cent, solution of nitric acid coloured by eosin shows these bodies 

 to be outside tbe vacuoles ; a concentrated solution of picric acid, acetic 

 acid, sulphuric acid, and potash lye, cause the exudation from these 

 bodies of strongly refringent oil-drops, as does also simply warming. 

 The oil-drops are coloured dark brown or black by a 1 per cent, solution 

 of osmic acid, a beautiful red by tincture of alcanna, and blue by 

 cyanin ; absolute alcohol dissolves them gradually. 



The elaioplasts are formed gradually in the epidermal cells during 

 the development of tbe leaf. The author found them also in Vanilla 

 aromatica, but not in Cypripedium latifolium. 



Structure of Starch-grains.J — Herr K. Mikosch has applied the same 

 mode of investigation to tbe discovery of tbe ultimate structure of starcb- 

 grains as that employed by Wiesner § in determining the structure of 

 the cell-wall. By laying for months in a 2 per cent, acid, hydrochloric, 

 sulphuric, or chromic, or by tbe application of chlorine-water and sub- 

 sequent pressure, be was able to break up potato-starch-grains into radial 

 apparently homogeneous rods. Five weeks' action of 2 per cent, hydro- 

 chloric acid produced no chauge except a slight swelling, and rendering 

 the stratification more conspicuous. In about three months the breaking 

 up of tbe starch-grains into minute but sharply defined rods has been 

 nearly completed. The ju'ocesses are nearly the same in wheat-starch, 

 but here the ultimate particles are granules, which can be made visible 

 by simply warming in water of 45° C. 



Tbe author concludes that the starch-grain is composed of minute 



* Maandbl. v. Natuurwetensch., 1887. See Bot. Centralbl., xxxiii. (1888) p. 361. 

 t Maandbl. v. Natuurwetensch., 1887. See Bot. Centralbl., xxxiii. (1888) p. 139. 

 X Mikosch, K„ ' Unters. iib. d. Ban d. Starkekomer,' Wien, 1887, 17 pp. and 5 figs. 

 § See this Journal, 1886, p. 818. 



