10U2 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Algae. 



New Genera of Florideae.* — Hcrr P. F. Rcinscli describes a number 

 of new species of Floiidca) from the island of S. Georgia, together with 

 the foUowing three new genera : — Chroa, a genus of Chordariaceae, with 

 an entire vesicuhxr frond witliout dissejiinients, near to Chordaria ; 

 Mcrcvia, a genus of lihodomelaccee, with fihimentoiis monosiphonous 

 frond, and transversely septate stichidia, intcnnediate between Poly- 

 si jjhnia and Dasya ; and Slraggaria, an epiiihytic genus, of whieh the 

 fructiticatiou is unknown, formiug subcouvex tubercles on Almfdtia 

 lAicata, the exact position of which is at present undetermined. 



Zygospores of Conjugatae.| — Herr H. Klebahn has followed out 

 closely the history of the nuclei of the two cells which unite to form the 

 zygote of the Conjugata) ; he finds it to differ in some cases from the 

 process as described by Schmitz and Strasburger. In several species of 

 SjJinxjyra there are in the young zygosi)ore still two distinct nuclei, 

 each with its own nucleolus. In this state it may remain some days 

 before the complete fusion of the nuclei. In the species of Zy(jnema 

 examined the complete coalescence of the nuclei appeared to take ])lace 

 much more rapidly. Among the Desmidiea?, he obtained in Closierium 

 (lunula) the remarkable result that even in the rijio zygote the two nuclei 

 still remained perfectly distinct. In another genus of desmids, Cylin- 

 drocystis (Brehissonii), the process more closely resembled that in 

 Zy>jnema. In the young zygospore was found a single nucleus, but 

 usually with two nucleoli. 



Spongocladia.| — Messrs. G. Murray and L. A. Boodle discuss tlic sjs- 

 tematic position of this genus of Areschoug's, referred by him to the 

 Siphoncpe, with which they identify Spongodendron Zanard. They 

 regard these alga) as probably more nearly allied to CladojAara than to 

 the Siphoneai, though closely resembling some genera of tliat family, 

 especially Codium, in external appearance. The thallus of S. vauclierise- 

 formis Aresch. consists of long filiform tubes so interwoven as to form a 

 number of irregularly dichotomous branches, the who'e recalling the 

 appearance of a digitate sponge. The tubes of which the branches are 

 composed are septate below, and short lateral branches are given off at 

 about a right angle from the cells. These serve to bind more closely 

 together the interwoven filaments. A probable formation of zoospores 

 was observed, which appear to germinate within the mother-cell. 



A remarkable feature of these algaa is the groups of siliceous sjiicules 

 which plentifully strew the course of the tubes. They are obviously 

 sponge-spicules, and are far more abundant than is consistent with a 

 merely accidental presence. Those found in connection with the different 

 species belong to the different sponges ; and the authors suggest that 

 there may possibly be some biological relationship of a symbiotic 

 character between the sponge and the alga. 



Aerophytic Species of TJlotricliaceae.§ — Dr. A. Hansgirg gives a 

 synopsis of the known species of the genera Hormidium, Horniiscia, and 

 iScJtizogonium, which he treats as belonging to the Ulotrichaceae. He 



* Ber. Deutsch. Bot. Gfsell., vi. (1888) pp. 144-56. t Ibid, pp. ICO-G '1 rl.). 



I Ann. of Bot., ii. (1888) pp. 1G9-75 (4 tigs.). 



§ Flora, Ixxi. (1888) pp. 259-06. Cf. this Journal, atite, pp. 4G5 and 775. 



