280 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Phytoplankton of St. Vaast-la-Hougue.* — L. Mangin reports on 

 the phytoplankton of the roadstead of St. Vaast, collected at the surface 

 layers. The volume is very poor in winter, increases in March, and 

 presents a first maximum in May or June, and a second more important 

 one in October to November. In winter the plankton is very dense, 

 formed of marine species. At other seasons it is flocculent, consisting of 

 species with long spines and refractory in settling. Peridinieae are rare, 

 whilst diatoms are remarkable for their abundance. The plankton is 

 homogeneous and very poor in species (May-Aug.) ; the rest of the year 

 it becomes heterogeneous and varied. The flora of St. Vaast is com- 

 pared with that of neighbouring regions. The great majority of the 

 species belong to the Didymus plankton. No representative of Styli- 

 plankton of the temperate regions is found, but only of the Trochoplankton 

 of the arctic and boreal regions. Of the 45 diatoms, two- thirds are 

 neritic of the temperate regions, and the remaining third belong to the 

 arctic regions. The prevailing ocean currents and their influence on 

 the phytoplankton are discussed. 



Plankton of Greifensee.j — 0. Gayer has examined the plankton of 

 the Greifensee, which he regards as possibly a former stretch of the 

 Linth blocked by a moraine. The phytoplankton contains 40 species. 

 Diatoms predominate in spite of the high temperature of the water. 

 The quick changes and the enormous number of individuals of the 

 various diatom-maxima in winter form a remarkable characteristic. 

 The principal species of plankton is Geratium hirundinella, with which 

 were compared the Ceratia of fifteen other Swiss lakes. He distinguishes 

 three different races: (1) " typicam" large lake type, with marked 

 seasonal variations, from large lakes where the water is not very warm ; 

 (2) " curtum," small, with less marked seasonal variation, in large and 

 small warm lakes ; 3. " palustris," pond type, very large in summer, 

 much reduced in winter, in ponds and very warm lakes. 



Antarctic Fresh-water Algae. $ — G. W. F. Carlson publishes a list 

 of the fresh-water algae collected by C. Skottsberg on the South Shet- 

 lauds, Graham Land, South Georgia, and the Falklands. New species 

 are described. The author criticizes former work on the Antarctic alga?, 

 aud gives a list of all fresh-water species recorded from the region, as 

 well as a complete bibliography. 



Swedish Fresh-water Algae. § — O. Borge writes on the fresh-water 

 algae of the Torre-Trask region in the north of Sweden. He records 

 442 species and varieties, some being described as new. Notes are 

 given on points of systematic interest. 



* Eecueil publ. a l'occasion Jubil. Sci. Prof. Le Monnier. Nancy : 1913, 

 pp. 141-55 (2 figs, in text). See also Bot. Centralb]., cxxv. (1914) p. 262. 



t Beitrage z. Biologie des Griefensees. Stuttgart : E. Scbweizerbart (1910) 

 96 pp. (6 pis.). See also Bot. Centralbl., cxxv. (1914) p. 185. 



% Wiss. Ergebn. scbwed. Siidpol. Exp., 1901-3, von O. Nordenskjold, iv. (1913) 

 pp. Ir94 (3 pis.). 



§ Bot. Not. Lund, 1913, pp. 1-33, 49-110 (3 pis. and 2 text-figs.). 



