CXX REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



Commission ; Mr. E. S. Eowland, of the Univerity of Michigan, and Mr. 

 It. C. Young. The superintendent of the station,Mr. J. J.Stranahan,and 

 others connected with the hatchery, rendered assistance throughout 

 the season. 



Professors Eeighard and Ward devoted some time to tlie designing, 

 construction, and experimental use of a number of pieces of apparatus 

 re(]uired in the plankton investigations, including a hydrophore (for 

 bringing up samples of water from any required depth), a large plank- 

 ton net, and an appliance for measuring the flow of water through 

 plankton nets. They also gave special attention to the determination 

 of the minute floating organisms preliminary to quautitativie plankton 

 work; 103 true plankton organisms were found, of which 6 were proto- 

 zoans, 4 rotifers, 9 crustaceans, and 84 alga?,. It is interesting to note 

 that Apstein records 82 plankton forms from the German lakes, G being 

 protozoans, 23 rotifers, 19 crustaceans, 2 spiders, 1 mollusk, 1 turbella- 

 rian, and 31 algj«. The scarcity of protozoans and rotifers in the Lake 

 Erie plankton, as regards both species and individuals, is somewhat 

 surprising, as these animals are abundant in Lake St. Clair and Lake 

 Michigan at the same season. The crustaceans are quite numerous as 

 to individuals, but not as to species, Avhile the algie are exceedingly 

 abundant as regards both individuals and species. The Lake Erie 

 plankton, therefore, as thus far studied, consists practically of alga? and 

 crustaceans. 



Dr. Jennings was engaged in the study of the piotozoans and rotifers 

 of the adjacent waters. The former were studied chiefly in an experi- 

 mental way, with special reference to the influences which determine 

 the movements of aquatic organisms and the laws by which they are 

 regulated. Taking the common ciliiited infusoriau, raramacium can- 

 datum, as a representative simjjle organism, its activities and reactions 

 to chemic stimuli were fully analyzed. The work was successful in 

 establishing general principles of much importance regarding the fac- 

 tors which govern the movements of such animals. Two papers of Dr. 

 Jennings, embodying the results of these studies, were published, by 

 permission of the Commission, in the American Journal of Physiology 

 for May, 1899. These were " The motor reactions of Faramcecium "and 

 " Laws of chemotaxis in Paramoecium.^- The region was found to be 

 exceedingly rich in protozoa, upward of 70 species being identified, 

 although these were only a small percentage of those observed. Tlie 

 adjacent swamps furnished many interesting species, including the 

 gigantic infusoriau, Jiursaria truncatella, Volvox, and other related 

 forms. Special attention was directed to the forms of which cultures 

 could be kept in the laboratory, so that they could be obtained in large 

 quantities. 



Studies of the rotifers were carried on from the systematic and 

 faunistic standpoints. The shore, bottom, and swamp rotifers were 

 exceedingly abundant, but those of the open waters were very scarce. 

 About 100 species of rotifers were identified, including some new and 



