ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 499 



gamete-nuclei takes place immediately after conjugation, before the 

 formation of the mesospore. The nucleus of the mature zygote never 

 shows a nucleolus. It disappears shortly after or even before the 

 fusion of the two gametse-nuclei, and only re-appears in the germinating 

 plants. Chromatin is finely distributed through the whole zygote-nucleus. 

 During the ripening of the zygote, the stroma-starch and the greater 

 part of the pyrenoid-starch are transformed into oil. The four chroma- 

 tophores still remain in the zygote, but with diminished circumference. 

 The pyrenoids also degenerate more or less. The membrane of the 

 mature zygote consists of three layers of epidermis. Exospore and 

 endospore are composed of cellules. The mesospore is composed of a 

 basal cellulose material, encrusted with cork-like substance. The 

 division of the zygote-nucleus, at the beginning of germination, is a 

 reduction, and is here described in detail. The four daughter-nuclei 

 remain, and are divided between the four resulting germlings. They 

 rest in the four chromatophores, which then divide. Each pair of 

 daughter-chromatophores, with its respective nucleus, provides one germ- 

 ling. Then the nucleolus appears again in the nuclei of the germlings. 



Pediastrum.* — Xitardy publishes an account of the genus Pedia- 

 strum. The species of Pediastrum Meyer, Microstomas Kiitz., and of 

 genera of Ehrenberg and Corda are passed in review ; also the species 

 included in the publications of later authors. As a result, he includes 

 nine species in the genus Pediastrum, which he ranges in five sections. 

 Each species is described. He discusses shortly the floating apparatus 

 of the species. He is of opinion that the bristles and bushy out- 

 growths are not continuations of the cell-membrane, but are pseudo- 

 podia-like prolongations of the protoplasm, which can be withdrawn at 

 will. Finally, the author gives a list of synonomy, a key, a systematic 

 table, and a full bibliography. 



Trentepohlia annulata in Moravia. f — S. Prat records the occurrence 

 at Trebitsch, in Moravia, of Trentepohlia annulata, growing on the roots, 

 and on sections of the stump, of fir-trees. It grew in small patches and 

 was in fruit. The species is recorded from Bavaria. A detailed 

 diagnosis is given. The specimens were identified by F. Brand, the 

 author of the species. 



Tertiary Dasycladacese from the Paris Basing — L. and J. Morellet 

 have published a completion and elucidation of Munier Chalmas 1 pre- 

 liminary account of the fossil Dasycladacee of the Paris basin, which 

 appeared in Comptes Rendus in 1*77. Up to the present no continua- 

 tion has been published, and the eighty-two genera therein enumerated 

 had never been described. The present authors have with great trouble 

 defined all the genera except six, and produced an exhaustive treat- 

 ment of the forms occurring in the Paris Eocene. The authors have 



* 



Beih. Bot. Centralb]., 2te Abt., xxxii. (1914) pp. 111-94 (10 pis.). See also 

 Bot. Centralbl., cxxviii. (1915) p. 158. 



t Oesterr. Bot. Zeitschr., lxiv. (1914) pp. 420-1. See also Bot. Centralbl., 

 cxxviii. (1915) p. 412. 



J Mem. Soc. Geol. Prance, xxi. No. 47 (1913) 43 pp. (3 pis. and 24 text-figs.). 

 See also Zeitscbr. Bot., vi. (1914) pp. 708-9. 



