ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 361 



chiefly Pleurococcus vulgaris and Scenedesmus caudatus — and lichen- 

 gonids, for the purpose of ascertaining whether they will still grow in 

 the dark when the assimilation function of chlorophyll is suspended. 

 He states that growth does take place, though with diminished energy, 

 in the dark, in a nutrient medium containing sugar and nitrogen in the 

 form of asparagin or ammonium nitrate. 



Cell-nuclei of Acrosiphonia.*— Prof N. Wille finds in this genus 

 of Algae two quite different types of cell-structure : — in one (A. bombycina) 

 each cell has only a single nucleus ; in the other type (A. hamulosa) the 

 cells are multinucleate. In both cases there is a relation between the 

 nucleus or nuclei and cell-division. The author proposes to remove 

 all the uninucleate species from Acrosiphonia, and place them under 

 Kutzing's old genus Spongomorpha. 



Botrydium granulatum. — M. L. Ivanoff f has followed out the life- 

 history of this alga, with the following results. 



Eypnosporangium is not a stage of Botrydium grannlatum, but an 

 independent organism. Botrydium granulatum Wor. et Eost. is made 

 up of three distinct species : — B. granulatum Grev., jB. Wallrothi Kiitz., 

 and Protosiphon botryoides Klebs. The root-cells are a stage of B. granu- 

 latum, and do not produce hypnosporanges. 



In B. granulatum Grev. the zoospores from one of the large bladders 

 give birth to the ordinary f«>rm, which may be propagated by zoospores, 

 spores, or root-cells. Zoospores may become transformed into spores, 

 and, after a time, may proliferate. The spores may either germinate 

 directly, or may produce fresh spores, or probably also zoospores. The 

 root-cells may either germinate directly, or may produce zoospores or 

 spores. 



In B. Wallrothi the zoospores, like the cells of B. granulatum, form, 

 on germinating, a bladder up to 500 jx in diameter. It is propagated 

 by spores and zoospores ; there are no root-cells, but, on the other hand, . 

 hypnosporanges. In both species zoospores and spores may arise in all 

 stages of development of the bladder. The zoospores may proliferate 

 or may form spores. The spores may produce new spores or zoospores, 

 or may proliferate. Hypnosporanges may give birth to either spores or 

 zoospores. 



Mr. H. Wager J gives a full description of this alga, including the 

 colourless underground rhizoids, the structure of which had not before 

 been described. He gives three different modes in which the non-sexual 

 swarmspores are formed, including the formation of hypnosporanges. 

 The alleged sexual reproduction by the conjugation of biciliated swarm- 

 spores is uncertain. 



Boueina, a Fossil Genus of Codiaceae.§ — In the Upper Neocomian 

 beds of south-east Servia, Herr G. Steinmann finds the remains of a fossil 

 alga, which he makes the type of a naw genus nearly allied to Ealimeda. 

 It has an unbranched cylindrical thallus ; the calcareous structure is 



* S.B. Biol. Selsk. Christiania, Nov. 30, 1899. See Bot. Centralbl., lxxxi. (1900> 

 p. 238. 



t Arb. k. St. Petersburg. Gesell. Naturf., xxix. (1898) pp. 1-10. See Beih. z. Bot. 

 Centralbl., ix. (1900) p. 163. % Proc. Leeds Nat. Club, iv. (1899) pp. 9-15. 



§ Ber. Naturf. Ges. Freiburg-i.-Br., xi. (1899) pp. (32-72. See Bot. Centralbl., 

 lxxxi. (1900) p. 346. 



