CONTRIBUTIONS TO THE BIOLOGY OF THE GREAT LAKES. 
ROTATORIA OF THE UNITED STATES, WITH ESPECIAL REFERENCE TO 
THOSE OF THE GREAT LAKES.* 
By H. S. JENNINGS, 
Instructor in Zoology, University of Michigan, 
INTRODUCTION. 
Among the objects to be attained in the biological investigations of the Great 
Lakes, inaugurated by the United States Fish Commission, a preliminary one is the 
collection and determination of the animals and plants found in the lakes and the 
placing of these on record. A portion of the first summer in the field (1898) was spent 
by the writer in a study of the Rotatoria of the region of Lake Erie about South Bass 
Island, where the summer laboratory was situated; the observations and collections 
there made form the basis of the present paper. Three summers had been spent previ- 
ously by the writer in study of the Rotatoria of other parts of the Great Lakes and of 
some of the inland lakes of Michigan; other observations in the Great Lakes have 
been made by Kellicott (’96 and ’97) on the Rotatoria of Lake Erie. These researches, 
taken together, make possible an extended, though of course incomplete, list of the 
Rotatoria of the Great Lakes. As the work on the Great Lakes has included the 
larger number of species observed in the United States, it has been deemed advisable, 
in this first report of work done for the United States Fish Commission, to include a 
record of all the Rotifera thus far observed in the United States, together with all the 
localities in which they have been observed, so far as possible. Notices of the Rotifera 
are scattered through many publications, and it is believed that nothing will serve 
better as a basis for future work than to bring these scattered notices together. 
In beginning a study of a circumscribed group of animals such as the Rotatoria, 
in connection with a general biological survey of the Great Lakes, it is well to have 
clearly in mind an outline of the problems upon which work is to be done. The lake 
is to be looked upon as an organism, the various groups of animals and plants in the 
lake, as well as the chemical and physical conditions and forces there present, being 
the organs which make up the whole. These organs are necessarily as closely corre- 
* The papers in this series are based on investigations of the U. $. Fish Commission, under the 
direction of Prof. Jacob Keighard, of the University of Michigan. Three other articles of the series, by 
the same author, have been published in the American Journal of Physiology, vol. ii, 1898 (pp. 311-341, 
and 355-379), and vol. in, 1900 (pp. 229-260), as follows: (1) The Mechanism of the Motor Reactions of 
Paramecium; (2) Laws of Chemotaxis in Paramecium; (3) On the Movements and Motor Reflexes of 
the Flagellata and Ciliata. 
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