ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 223 



springs ; after the collapse of the parent this cell is cast off like a 

 propagule. 2. An asexual planospore which comes to rest, develops a 

 membrane, and undergoes a certain period of rest. 3. A zygote, as yet 

 unobserved by the author, but of undoubted existence. Each of these 

 three varieties of cell develops. first into a small vesicle here described in 

 detail, a syncytial blastea formed of juxtaposed plastids, and clothed 

 with a general cuticle. This blastea is the faithful representation of an 

 ancestral primitive stage. It throws out, above, a tube rich in deeply- 

 coloured chromatophores ; and, below, a rhizoid containing nuclei and 

 chromatophores, which at once lose their colour. The aerial tube forms 

 a vesicle, of which the author defines three kinds, according to the 

 nature of the cells which they produce. The development of each is 

 described in detail. The essential productiou of the first kind is a 

 number of small cells surrounded with a cellulose cuticle, which after the 

 bursting of the mother-cell are disseminated by rain and germinate. In 

 the second kind asexual planospores are produced which, after escaping 

 from the burst mother-cell, have a short period of activity, and then 

 settle down and germinate in the same way as the cells of the first kind. 

 The third kind of vesicle produces a " gametangium," homologous with 

 the oogonium and spermogonium of Fums. The author has observed 

 all the stages of development except the emission of the flagella of the 

 gametai, and their subsequent movement and coalescence. In a diagram 

 are sketched out the various aspects of the ontogenesis of the plant. 



E. S. G. 



Algological Notes. XXV.-XXIX.— N. Wille {Nyt Mag. Natur- 

 videnskah. Christiania, 1918, 56, 61, 2 pis.). The first of these notes, 

 No. XX Y. of the series, deals with variability in the genus Scenedesmus 

 Meyen. The author discusses critically the work of former authors, 

 and emphasizes the importance of wide views in regard to the occur- 

 rence of variation. He describes the germination of aplanospores in 

 S. hijugatus Klitz., the stages of which vary greatly from the normal 

 form. These stages must not, however, be regarded as constituting 

 polymorphism; nor may also the aberrant forms produced under adverse 

 conditions. The vegetative forms of S. obliquus Klitz. and S. hijugatus 

 respectively are described. The former was found varying in the 

 number of its component cells from one to eight, four and eight being 

 the most common. In S. hijugatus the same variation occurred, but 

 the numbers other than four and eight were much more rarely found. 

 In Note XX YI. the germination of the aplanospores in the genus 

 Ccelastrum Nag. is described. No. XXYII. gives a list of the fresh- 

 water alg^e of Beeren Island, containing fifty-five species and varieties 

 of Chlorophycese and Myxophyceee, sixteen of which are not yet recorded 

 from Spitzbergen. No. XXYIII. : The name of Lynghya ejyiphytica 

 Wille, a marine species, is changed to L. Willei Setchell & Gardner, 

 the former specific name having been previously used in the genus for 

 a fresh-water species. In Note XXIX. the author continues his studies 

 in Agardh's " Herbarium," interrupted since 1913. Haematococcus san- 

 guineus proves to be Gloeoca'psa sanguinea Kiitz. Meneghini's specimens 

 of Microcystis bullosa (Kiitz.) Menegh. and M. gelatinosa jVIenegh. 



