196 SUMMARY OF CURRENT RESEARCHES RELATING TO 



flora is explained by the author in a plausible theory, which is that the 

 Desmids are constantly being renewed from the surrounding moss- 

 covered hills and bogs which are their natural habitat. He points out, 

 too, that adaptation to their new habitat is gradually taking place, as is 

 shown in the elongation of spines, etc. The quantity of plankton in 

 the Highland lochs is very poor relatively, and the effect of the more 

 even temperature in Scotland is shown by the far less pronounced 

 seasonal change than is found in the Danish lakes. The water of 

 Scotch lochs is not affected in colour by the plankton, and the deposition 

 of organic matter is small. The depth of the Scotch lochs is greater 

 than that of the Danish lakes, and they are also of a more permanent 

 character. 



Phytoplankton of Lake Thau.* — J. Pavillard has made a detailed 

 study of the phytoplankton of this small lake, near the zoological 

 station of Cette. He divides his paper into four parts. The first 

 is devoted to a general description of the lake, considered from the 

 geographical and physiographical point of view. The second part treats 

 of the vegetation in the environs of the lake, namely, that of the dunes 

 and dry sea-sand, the damp sand and brackish water, and the phyto- 

 benthos. This leads on to the principal part of the paper, which deals 

 with the phytoplankton from the quantitative and qualitative points of 

 view. The species found are enumerated, and references are given to 

 synonyms and literature, as well as occasional notes as to the season of 

 of greatest abundance of the species. The fourth section deals with 

 questions of distribution, and with formations and associations. A list 

 of bibliography is followed by a map of the lake and its surroundings, 

 and three plates. 



Plankton from the Schonenbodensee.f — M. Tanner-Fulleman 

 describes a new plankton organism, Rhapidium Ghodati, and gives lists of 

 the summer and autumn plankton of the above-mentioned lake near 

 Wildhaus, in St. Gall canton. R. Ghodati occurs abundantly, Geratium is 

 rare, and Asterionella gracillima is usually absent. 



Phytoplankton of the Antarctic Ocean.} — G-. Karsten's report on 

 the phytoplankton collected by the German Deep-sea Expedition, on 

 board the 'Valdivia,' not only brings together for the first time a 

 complete list of Antarctic species, but also deals with questions of 

 supreme interest regarding the distribution, biology, and development 

 of plankton algas. His work deals with the vertical distribution of the 

 species and the qualitative variation in the successive zones of depth 

 the effect of light and darkness on certain genera ; on dimorphism 

 resting spores ; microspores ; the effect of ocean currents on distribu 

 tion ; and many other equally important subjects. The bulk of living 

 plant-organisms is almost entirely confined to the upper layer of 200 m., 

 the maximum occurring between 40-80 m. The nature of the plankton 

 characteristic of the different depths is analysed. In the systematic 



* Inst. Bot. Universite Montpellier, Mem. 2 (1905) 116 pp., map, 3 pis. 

 t Bull. Herb. Boissier, vi. (1906) pp. 156-8 (1 pi.). 



j Wiss. Ergeb. deutscb. Tiefsee-Expedition- Valdivia, 1898-99, ii. Jena, 1905, 

 19 pis. 



