ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 347 



that algal cultures which contain only certain of- the Volvocacese can be 

 obtained by inoculating decaying albuminous bodies with different mate- 

 rials. The species obtained are Chlorogonium euchlorum, certain Chla- 

 mydomonads, Spondylomorum quarternarium, and Polytoma uvella. If 

 these experiments are carried out in the dark, P. uvella and sometimes 

 Chlorogonium euchlorum are developed. The calcium salts of different 

 organic acids, as well as the organic acids produced by the decomposition 

 of cellulose and pectin, are very suitable for the accumulation of a cer- 

 tain green species of the Volvocaceaa, Carter ia ovata, here described as a 

 new species. The occurrence of these algae must be a verv common one. 

 They are all very sensitive to acids, but less so to alkalis. By a slight 

 deficiency of oxygen they produce through carbonic-acid assimilation a 

 great quantity of oxygen, and by this means they promote powerfully 

 the cleansing of dirty water. The cultivated Volvocacege show, with 

 the exception of Polytoma uvella, a strong sensitiveness to light, and 

 re-act positively as well as negatively phototactically, according to the 

 intensity of lio-ht and to their reaction to light, this last being influenced 

 by different factors. By means of this phototactic quality, and their 

 different behaviour in drying, it is possible to divide the species from 

 each other to a certain extent and to purify from bacteria. Pure cultures 

 can be obtained of most of them by the usual bacteriological methods, 

 since they form colonies on firm nutritive substrata. The decomposition 

 products of albumen have the greatest significance for the organic nutri- 

 tion of these organisms, through the action of trypsin ; for Carteria ovata 

 the organic calcium salts are sufficient. The above-mentioned algas be- 

 long, with the exception of Polytoma uvella, which is purely saprophytic, 

 to the decidedly myxotrophic organisms. 



Serbian Desmids.* — P. Georgevitch gives a list of 199 species, 

 belonging to nineteen genera, which were collected by himself and his 

 brother in the months of June and August in moorland lakes above 

 Wlasina in Serbia. These lakes lie on a plateau 1219 metres above sea- 

 level, called the Wlasina-See. Up to the present time only ten genera 

 with sixteen species had been recorded for Serbia, so the present list 

 greatly enlarges the known desmid flora for that region. One new 

 variety, Cosmarium cuAatum Ralfs var. coronatum, is described and 

 figured. 



Desmids from Macedonia.! — P. (Jeorgevitch enumerates 123 species 

 of desmids from the Prespasee in Macedonia. One or two short critical 

 notes are added. 



Catalogue of Portuguese Diatoms.! — C. Zimmermann publishes a 

 list of the species of Portuguese diatoms, which he issues in his second 

 and third centuries, and adds localities to each record. Almost all the 

 species enumerated are new to Portugal. 



Diatoms of Madeira and Porto Santo.§ — C. Zimmermann records 

 115 species of diatoms from Madeira and Porto Santo, from which 

 localities only three species have- as yet been made known. He gives a 



* Beih. Bot. Centralbl., xxvi. (1910) pp. 189-204 (2 pis.). 



t Tom. cit., pp. 237-46 (figs.). 



X Broteria, viii. (1909) pp. 89-103. § Tom. cit., pp. 114-27 (1 pi.). 



