ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 183 



Slime on Trees.* — F. Ludwig gives a list of the animal and vege- 

 table organisms observed on the slime of various trees — apple, beech, 

 horse-chestnut, &c, during 1898. Tne latter include Algae, Schizo- 

 mycetes, and several families of Fungi. The author regards lightning 

 as a frequent cause of this flow of slime. 



Stigmonose.f— Albert F. Woods has determined tbat this disease of 

 pinks is due, not, as has hitherto been supposed, to a schizomycete, 

 Bacterium Dianthi, but to the attacks of insects, especially of Rhopalo- 

 siphon Dianthi and of species of Thrips. 



B. CE.YPTOGAMIA. 



Cryptogamia Vascularis. 



Fertilisation in Aspidium and Adiantum.J — C Thorn has followed 

 out the process of impregnation in several species belonging to these 

 two genera of ferns. As the spermatozoid enters the mouth of the 

 archegone, it consists of a proximal cytoplasmic portion of about one 

 and a half coils, and a distal nuclear portion of about two spiral coils. 

 The cytoplasmic portion is derived from the blcpharoplast, and bears 

 numerous long cilia. It either becomes entirely disconnected from the 

 rest of the spermatozoid before entering the oosphere, or becomes func- 

 tionless and is dragged passively along. The sperm-nucleus consists 

 of an outer homogeneous chromatin mass and an inner ground-substance 

 derived apparently from the nucleoles of the spermatid. The whole 

 body is surrounded by a cytoplasmic envelope. As soon as the nucleus 

 has entered the archegone, it is attracted by the oosphere-nucleus inde- 

 pendently of its ciliated anterior end. Before fertilisation the sperma- 

 tozoid is found coiled in a depression in the oosphere. The oosphere- 

 nucleus has a branching irregular form extending through the cytoplasm 

 in all directions. It contains one or more prominent nucleoles, and a 

 network bearing extremely minute chromatin-granules. The nuclear 

 coils of the spermatozoid lying in the concavity of the oosphere make 

 their way towards its nucleus ; and, as soon as it reaches the nuclear 

 membrane, it breaks through it, and, escaping from its cytoplasmic 

 envelope, passes unchanged into the oosphere-nucleus. After entering 

 the oosphere-nucleus, the sperm-nucleus at once assumes a resting stage 

 by breaking up into the nuclear network, bearing flue chromatin-granules. 

 This network is from the first so fused or entangled with the network 

 ot' the oosphere-nucleus that it is impossible to distinguish any differ- 

 ence between the sexual elements after the form of the spermatozoid 

 has disappeared. 



Regenerating Buds of Cystopteris.§— J. Palisa states that the re- 

 generating buds of Cystopleris bulbifera and montana originate exclu- 

 sively from epidermal cells ; all the epidermal cells near the base of 

 the leaf on its upper side possess the property of regeneration. Com- 

 paring the formation of the adventitious buds on fern-fronds (Cystopteris 



* Zeitsehr. f. Pflanzenkrank., ix. (1S99) p. 10. See Bot. Oentralbl., lxxxiv. 

 (1900) p. 295. 



t U.S. Dptmt. Agric. (Div. Veg. Phys. & Path.), Bull. No. 19, 3 pis. and 5 figs., 

 1900. % Trans. Acad. Sci. St. Louis, ix. (1899) pp. 285-314 (3 pis.). 



§ Ber. Deutsch. Bot. Ges., xviii. (1900) pp. 398-410 (1 pi.). Cf. this Journal, 

 1900, p. 611. 



