ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 83 



Oil in Vaucheria.* — P. Fleissig inclines to the view that tho oily 

 substance found in the filaments of Vaucheria is a reserve substance, 

 analogous physiologically to starch, rather than a product of assimila- 

 tion or of degeneration. It is never accompanied by starch, tannin, 

 cane-sugar, or aldehyd, and by only traces of glucose. The oil-drops 

 are always found in connection with chloroplasts, but not enclosed within 

 the chlorophyll-bodies. 



Fungi. 



Gametogenesis and Fertilisation in Albugo.f — F. L. Stevens has 

 further followed cut the life-history and phenomena of impregnation in 

 four species of Albugo, A. Candida, Bliti, Portulacse, and Tragopogonis, 

 and has arrived at the following general conclusions. 



A. Portidacse possesses a multinucleate oosphere ; the nuclei all pass 

 to the periplasm, dividing mitotically ; some of the daughter-nuclei re- 

 -enter the ooplasm and divide again, their products becoming the female 

 nuclei, the plasmoderma being in the meantime differentiated. Two 

 mitoses occur in both oogenesis and spermatogenesis. The nuclear 

 figuro of the second mitosis is clearly distinguishable from tho first by 

 the diminished kinoplasm. The antheridial tube is multinucleate. The 

 numerous antheridial nuclei fuse in pairs with the numerous oospheric 

 nuclei ; these fusion nuclei passing the winter without further change. 

 A ccenocentrum is present. The receptive papilla is larger than in the 

 other known species. 



In A. Tragopogonis a multinucleate oosphere develops in the same 

 manner, and is then reduced to a uninucleate condition by disorganisa- 

 tion of the supernumerary nuclei. The nuclei pass to the periplasm, 

 divide, and return to the ooplasm much diminished in achromatic con- 

 tent. Two mitoses occur in oogenesis and in spermatogenesis. The 

 nuclei figure of the second division may be distinguished from the first 

 by a diminution of kinoplasm. The antheridial tube conveys one or 

 more nuclei into the oosphere, where one fuses with the female nucleus. 

 Both the supernumerary male and female nuclei disorganise. The 

 fusion-nucleus undergoes repeated mitosis, and the winter oosphere is 

 consequently multinucleate. The ccenocentrum is very highly developed ; 

 it possesses an attraction for the primary oospheric nuclei, and serves as 

 a source of nourishment for the surviving female nucleus. 



In A. Candida the oosphere is developed in a manner quite different 

 from that in the other three species. The periplasm and ooplasm are 

 not differentiated until the second mitosis is completed. The nuclei, 

 excepting one, eventually pass to tho periplasm, which is then cut oft 

 by a wall. One nucleus remains in the oosphere attached to the coeno- 

 centrum. The ccenocentruin attracts the nuclei very strongly, and later 

 serves as a source of nourishment for the surviving female nucleus. The 

 antheridial tube occasionally contains two nuclei. 



The processes leading to zonation may be regarded as the differentia- 

 tion of an ooplasm rich in trophoplasm. Tho cell-plato is formed, with- 



* Ueb. d. phys. Bedentung d. oelartigen Einschllisse in d. Vaucheria, Basel. 1900. 

 46 pp. See Bot. Centralbl., lxxxvii. (19i»l) p. 340. 



t Bot. Gazette, xxxii. (1901) pp. 77-98, 157-69, 238-61 (4 pis. and 9 figs.). Cf. 

 this Journal. 1900, p. 92. 



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