342 SUMMARY OF CUKRENT RE.SEARUHP:8 RELATING TO 



forms, with tables showiiif^ their distribution in Iceland itself and their 

 wider distribution in the Arctic region and in the five continents of the 

 world. As the number of forms previously recorded for the island was 

 131, the result of the author's work is to make the total about 3| times 

 as large, xlppended is a list of the forms found in hot springs, and 

 mostly in the living state; these represent 178 species and varieties, and 

 31 genera. A. G. 



Photosynthesis in Fresh-water Algae. — B. Mooee and T. A. 

 Webstee {Proc. Roy. Soc, Ser. B., 1920, 91, 201-15). A discussion 

 of the fixation of both carbon and nitrogen from the atmosphere by 

 green plant cells, to form organic tissue. Experiments show that in the 

 absence of all sources of nitrogen, save the atmosphere, unicellular algse 

 can, in presence of abundant COg, fix N", grow and form proteins ; but 

 the rate of fixation and growth is much accelerated if nitrites or oxides 

 of nitrogen are available. Such oxides of nitrogen occur normally in 

 pure country air, especially in spring and summer. Formaldehyde and 

 methylic alcohol — products of photosynthesis — are very poisonous to 

 the green cell ; but when extremely diluted they are found, in the 

 absence of COg, to be nutritious to the cell. A. G. 



Review of the Genus Chlorochytrium. — B. M. Bristol {Joiirn. 

 Linn. Soc, 1020, 45, 1-28, 3 pis., 1 hg. in text). In an historical intro- 

 duction the author recalls the work of Prof. G. S. West in submerging 

 six other genera into Chlorochytrium, and his suggestion that similar 

 drastic revision was needed for the species of the genus. She shows that 

 certain characters used for the limitation of the species are too variable 

 to have specific value. These are the shapes of the cells, the nature and 

 extent of the thickenings of the cell-walls, the form and size of the 

 chromatophore, and the fusion or asexual development of the zoogonidia. 

 Thus she has been able to reduce the number of species to ten, and of 

 each of these she gives a full and critical account, with varieties. This 

 is followed by a summary of the species wdth synonyms, references to 

 literature, diagnosis and habitat. Three doubtful species are shortly 

 described, w'hich in the absence of authentic material are impossible to 

 identify. Finally, a note is added on C. glwophilum Bohlin, which is 

 probably only a form of G. Facclolase Bristol. The plates represent 

 preparations of C. Lemnse and C\ paradoxum. E. S. G. 



Studies on the Chloroplasts of Desmids. IV.— Nellie Carter 

 {Annah of Botany, 1920, 34, 303-20, 3 pis.). The first part treats of 

 the chloroplasts of Staurastrum. Mostly these are axile ; only in 

 S. tumidum were they found to be parietal. ]\Iany of the smaller 

 species have a simple axile chloroplast consisting of a central axis which 

 contains a single pyrenoid and a ])ilol)ed mass projecting into each angle 

 of the semi-cell. Amongst the larger species the general form of the 

 chromatophoi-e is often quite similar to that of the smaller ones, but 

 there are variations in the number of plates in each angle and also in 

 the number and arrangement of the pyrenoids. Most of the species 

 examined had one point of pyrenoid formation in the centre of the 



