Biologisches Centralblatt 



unter Mitwirkung von 



Dr. M. Reess uud Dr. E. Selenka 



Prof, der Botanik Prof, der Zoologie 



herausgegeben von 



Dr. J. Rosentlial 



Prof, cler Physiologic in Erlangen. 



24 Numrnern von je 2 4 Bogen bilden einen Band. Preis des Bandes 20 Mark. 

 Zu beziehen durch alle Buchhandhmgen und Postanstalten. 



XV. Band. i. Mai 1395. Hr. 9. 



Inhalt: BirgC, On the vertical distribution of the pelagic Crustacea of lake Mendota, 

 Wis., during July, 1894. - Lliciani, Ueber Ferrier's neue Studien zur 

 Physiologic des Kleiuhirus. - KucllS, Kann eiu zu einem Eisklumpen ge- 

 frorenes Tier wieder lebendig werden ? Zachai'ias, Ueber den Unterschied 

 in den Aufgaben wandernder und stabiler SiiCwasserstationen. 



On the vertical distribution of the pelagic Crustacea of lake 

 Mendota, Wis., during July, 1894. 



By E. A. Birge, 



Professor of Zoology, University of Wisconsin. 



During- the month of July 1894 a careful study was made of the 

 vertical distribution of the pelagic Crustacea of lake Meudota, a body 

 of water about 10 kilometers long by G in width. The greatest depth 

 does not much exceed 25 meters. Not far from the laboratory of the 

 University of Wisconsin a depth of over 18 meters can be found and 

 here most of the observations were made. 



By means of an automatic vertical dredge the Crustacea were 

 obtained from the different depths of the lake, intervals of three meters 

 being used. This gave six levels in the total depth. The number of 

 Crustacea from each level was determined by counting. Four species 

 were found numerous enough to be used in determining the vertical 

 distribution. These were Diaptomus oregonensis Lillj., Cyclops brevi- 

 spinosus Her rick and leuckartii Sars. (counted together), Daphnia 

 hyalina Ley dig, and D. pulex var. pulicaria Forbes. The last 

 species is near D. Schoedleri Sars. 



The results may be summarized as follows: 



1) 59 complete series of catches were made, 26 of which were 

 between 9 p. in. and 3 a. m., and 33 beetween (3 a. m. and G p. m. 

 They were made at intervals of three hours on observing days, except 

 when strong winds made it impossible to go out. 



XV. 23 



