ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 793 



beloncrin» to all yellow fatty pigments, there are two adflitional ones, 

 one at G, the other between E and h. In addition to the lipochronie, 

 there was found, in each of the four species examined, an amorphous 

 pigment soluble in water, and of an acid character. 



Protophyta. 

 a. Schizopliyceae. 



Growth of the Cell-wall by Intussusception in some Schizo- 

 phycese.* — Herr C. Correns states that in Gloeocapsa and Petnlonema 

 certain definite layers of the cell-wall increase in volume, although 

 separated by similar layers from the protoplasm of the cell. Since this 

 is not accompanied by swelling, it can only be brought about by the 

 intercalation of water and particles of substance between those already 

 in existence. The proofs that the increase in size is not the result of 

 swelling are given in detail. 



In Petalonema it is not the apical cell alone, but all its segments to 

 a certain distance from the apex that divide. The gelatinous sheaths 

 are formed from the apex, and are usually of a funnel-shape, and 

 probably formed by apposition. The entire sheath is inclosed in a 

 pellicle, which, through growth by intussusception, keeps pace in 

 volume with the sheath, and is not burst or broken through by the 

 growth of the funnels. The sheath, and especially the junction of the 

 inner and outer sheath, is coloured yellow or brown-yellow by scyto- 

 nemin. The presence of the pellicle and the thickness of the sheath 

 distinguish Petalonema from Scytonema. 



Prasiola.t — Herr L. Imhiiuser separates Prasioln from the Ulvaceae, 

 and erects it, possibly along with Protoderma and Schizomeris, into a 

 distinct family of Prasiolace^e, nearly allied to Palmellaceje. All the 

 species consist, when mature, of a larger or smaller plate of cells ; and 

 are distinguished from the Ulvacefe by the mode of reproduction, which 

 is a purely non-sexual one, and takes place by the plate breaking up 

 into larger or smaller areolae, or more usually into single cells ; less 

 often filaments of cells are split off". From the isolated cell is always 

 developed a filament, which then grows into a plate. Hormidium and 

 ScJiizogoniiim are merely stages in the development of these plates. 

 The following six species are described, the first alone being free, all the 

 rest attached : — P. crista, furfuracea, siipitata, Sauteri, ccdophylla, and 

 mexicana. 



Heterocystous Nostocacese.l — Supplementing Bornet and Flahault's 

 monograph of the heterocystous Nostocacese contained in the herbaria of 

 France, M. E. Bornet now describes the specimens contained in the 

 herbarium of Agardh, many of which are the type-specimens of the 

 Systema Algarum. 



Movements of Diatoms.§ — From observations made on various species 

 of Navicula, especially of the sub-genus Pimmlaria, Herr 0. Miiller 

 confirms his previous hypothesis that the movements of these diatoms 

 ai"e connected with perforaticjns in the cell-wall. He finds that immer- 



* Flora, Ixxii. (1889) pp. 298-347 (1 pi. . t T. c , pp. 283-90 (4 pis.). 



t Bull. Soc. Bot. France, xxxvi. (1889) pp. 144-57. (Si. this Journal, 1888, 

 p. 472. 



§ l!cr. DcutM-h. Bot. Gcscll., vii. (1889) pp. 160-^0 (I pi.). 



