210 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Lemmermanni Richter, through June to the beginning of July ; and. 

 Fragilaria crotonensis Kitton, during July. II. Schizophycete period. 

 Gloiotrichia echinulata Richter, July to August ; Clathrocytis aeruginosa 

 Henfr., Oct. to Nov. III. Second BaciUaria period. Melosira distant 

 var. Icevissima Grim., December to January. 



These species occur in masses during the periods stated. The 

 author attributes the periodicity to change of temperature and to the 

 varying quantity of silicic acid in the water. Details are given of the 

 plankton of the other lakes. Several new varieties are described for 

 species already known, as well as a new genus and species, Botryodictyon 

 elegans. Changes of nomenclature are brought forward, and remarks 

 are made on the free-swimming species of Lynybya and the genus 

 Hyalobryon, as well as various other species. 



Studies on Phytoplankton.* — C. H. Ostenfeld publishes his second 

 and third studies on this subject. The former is on a sample from a lake 

 in South Iceland, collected by H. Jonsson. The main part of the sample 

 consists of diatoms, among which Biatoma hiemale occurs in long bands 

 like a Fragilaria, and is here recorded for the first time as a plankton 

 form. Neither Tabellaria nor Cyclotella occur in the sample. A great 

 quantity of Tribonema bombycinum Derb. et Sol. forma depauperata 

 Wille, was found, but the other green alga? were few and only in single 

 specimens. The author considers that the plankton of this lake is like 

 that of the lowland lakes of Northern Central Europe and Southern 

 Scandinavia, but much poorer, especially by the lack of the summer 

 forms. 



The latter of these studies deals with the phytoplankton from some 

 tarns near Thorshavn (Stromo) in the Faeroes. This work is supple- 

 mentary to the author's paper published with Professor Borgesen. The 

 results are tabulated. Very few diatoms were obtained in four of the 

 five tarns examined, but in the fifth they were predominant. P&ridinium 

 Willei was abundant. 



Classification of Protophyta.f— C. E. Bessey publishes a revision 

 of the families and a rearrangement of the North American genera. He 

 divides the Schizophyceae into two orders — Cystiphoras and Nemato- 

 geneae — the first being 1-celled, the second filamentous. Cystiphora) 

 consists of the Chroococcaceae, and Nematogeneaa contains Oscillariacea), 

 Rivulariaceaa, Scytonemaceae, Nostocacese, Sirosiphoniaceaa. Keys are 

 given to the genera in each family, and each genus is described. 



Remarks on Glceocapsa.J — Gr. T. West describes the life-history of 

 Glaiocapsa crepidinum, which occurs on mud, etc., in salt or brackish 

 water. Seven stages in the life-history are figured in colours. The 

 thick hyaline integument is not a gelatinised cell-wall, but is excreted 

 by the cell. Multiplication takes place by simple cell-division. The 

 daughter-cells secrete each their own integument, being still enclosed, 

 within the much stretched mother-cell integument. Thus colonies of 

 two or four with lamellated integument are formed. Finally, the young 



* Bot. Tidssk., xxvi. (1904) pp. 231-9. 



t Trans. Amer. Micr. Soc, xxv. (1904) pp. S9-104. 



X Trans. Edinb. Field Nat. and Micr. Soc, v. (1904) pp. 130-3 (1 pi.). 



