558 SUMMARY OF CURRENT RESEARCHES RELATING TO 



they are formed by successive bipartitions. On germinating, the ante- 

 rior colourless end developes into the rhizoid. Under unfavourable 

 vital conditions Urospora forms resting-cells. 



Chionyphe.* — According to Dr. G. B. de Toni, this genus of snow- 

 Algas proposed by Thienemann, is nothing but the protoneme of a 

 moss, probably an Andresea or Bryum. The genus Kurzia of Martens 

 again, possibly consists of the very reduced leaves of a Jungermannin. 



Grenacantha, previously identified by de Toni with Bulhochsete, he 

 now regards as more probably belonging to the Cladophoraceae, possibly 

 near Chlorojpteris Mont. 



Avrainvillea.f — Messrs. G. Murray and L. A. Boodle give a diagnosis 

 and monograph of this tropical genus of Multinucleatae, with which they 

 identify Mhipilia and GMorodesmis, placing it near to Penicillus and 

 Udotea, from which it differs in the absence of any calcareous incrusta- 

 tion. Nine species are described, one of them new. The mature plant 

 is, when not in a reproductive condition, almost absolutely non-cellular. 

 The filaments are dichotomously branched, and are more or less inter- 

 woven, so as to form a stalked or sessile frond above, a mass of 

 rhizoids below ; the filaments are constricted, and very rarely septated, 

 near their base. The protoplasm forms in most cases a rather thin 

 parietal layer, through which are distributed the chlorophyll-grains and 

 a very large number of nuclei, which are usually considerably larger than 

 the chlorophyll-grains and much more granular. A yellowish or 

 brownish colouring-matter is distributed through the protoplasm. The 

 frond is always more or less flabelliform, and usually more or less 

 felt-like in texture. The mode of reproduction was not observed. The 

 authors suggest that the gigantic fossil siphoneous alga Nematophycus, 

 from the Devonian, was possibly allied to Avrainvillea. 



Cellulose-fibres of Caulerpa.} — Herr F. Noll proposes a different ex- 

 planation from that hitherto accepted for the fibres or bands of cellulose 

 found within the greatly enlarged cell of Caulerpa jproUfera. He shows, 

 from various considerations, that their purpose cannot be the mechanical 

 strengthening of the organism, and adduces evidence in favour of the 

 view that they serve as a channel for the conveyance of nutrient sub- 

 stances more rapidly than this can take place through the protoplasm. 

 They serve in fact the purpose of intervening a large surface between 

 the internal protoplasm and the atmosphere, and may be compared vrith 

 the external protuberances from the greatly enlarged cell of Godium. 

 Gaulerpa presents in this way the greatest differentiation of structure to 

 be found in any non-cellular plant. The division into cells of the cellular 

 plants must be regarded mainly as a contrivance for the same purpose, 

 the easy transference of food-material, rather than as a splitting up into 

 physiological units. 



Volvox.§ — Dr. L. Klein makes a further contribution to our know- 

 ledge of the morphology and life-history of this genus, his observations 

 having been made chiefly on F. aureus Ehrb. ( = F. minor Stein). 



* Ber. Deutsch. Bot. Geeell., vii. (1889) pp. 28-30. 



t Journ. of Bot., ixvii. (1889) pp. 67-72, 97-101 (2 pis.)- 



X Arbeit. Bot. Inst. Wurzburg, iv. (1888) pp. 459-65. 



§ Jahrb. Wiss. Bot. (Pringsbeim), xx. (1889) pp. 133-210 (3 pis.). Ber. Deutsch. 

 Bot. Gesell., vi. (1888) Gen. -Vers. -Heft, xcix.-ci. Op. cit., vii. (1889) pp. 42-53 

 (1 pl). 



