ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 313 



that during the day the Entomostraca, which constitute the great bulk 

 of the fauna, sink down to escape the strong light, and rise again to the 

 surface during the night. This observation confirms those of Yung. 



Tropical and more Northerly Plankton.* — Mr. I. C. Thompson re- 

 ports on two collections made by Captain F. H. Wyse aud Mr. G. W. 

 Herdman by means of tow-nets fixed to running water-taps on board 

 two steamships, — a method successfully pursued by Prof. Herdman. The 

 one collection included 70 species, the other 39 species of Copepods. 

 The notes show, in almost all cases, an extension of the hitherto known 

 range of geographical distribution. " Our further knowledge of these 

 minute Crustacea which play so important a part both as ocean 

 scavengers and as themselves a very important constituent of the food 

 of fishes and other animals, would be largely increased if other navi- 

 gators would kindly, in the interest of science, follow the example of 

 Captain Wyse and Mr. Herdman, and so enable us to have collections 

 from all parts of the world." 



Plankton of Fresh- water Lakes.j — Mr. C. D wight Marsh gives a 

 useful account of the problems and methods of lacustrine plankton re- 

 search, and a summary of results attained with especial reference to his 

 own experience of North American lakes. The usefulness of the address 

 is increased by the hints that are given as to the most profitable lines 

 of work. 



Lake Plankton.^ — Dr. 0. Fuhrmann studied the plankton of the 

 Lake of Neuchatel from October 1896 to September 1897, and compares 

 his results with those of other observers (Apstein aud Zacharias) on 

 the lakes of North Germany. Neuchatel proves to be less rich in 

 plankton than the northern lakes, aud shows other striking differences. 

 There are two marked maxima, in Decemher and May respectively, and 

 two marked minima, in March and August. The latter are due to the 

 poverty of Algae, Daphnids, and Copepods ; the December maximum to 

 the abundance of Asterionella, Fragilaria, Bytltotrephes, and Bosmina'; 

 the May maximum to the last two and also to Dinobryon, Cyclops 

 strenuus, and Daphnia hyalina. In the Swiss lakes the surface, so rich 

 in life in the German lakes, is almost devoid of life during the day, the 

 Copepods, Daphnids, and Rotifers performing daily migrations not indi- 

 cated in the northern lakes. This the author ascribes to the extreme 

 transparency of the Swiss lakes, which renders the illumination of the 

 surface waters too intense during the day for animals sensitive to light. 



Swiss Plankton. § — Dr. G. Burckhardt publishes an elaborate and 

 thorough paper on the animal plankton of the larger Swiss lakes. Its 

 scope may be indicated by the following brief list of headings. Under 

 the title of hydrography we have a general discussion of the physical 

 geography of the lakes, their classification, aud general characters. 

 This is followed by a faunistic part, which gives lists of the organisms 

 obtained in the lakes, with authorities and references in each case, and 

 then by a systematic section in which the systematic position and rela- 



* Trans. Liverpool Biol. Soc. xiv. (1900) pp. 262-94 (1 pi. and 3 figs.). 



t Science, xi. (1900) pp. 374-89. 



1 Arch. Sci. Phys. et Nat., viii. (1899) pp. 485-7. 



§ Rev. Suisse Zool., vii. (1900) pp. 353-713 (5 pis.). 



