REPORT OF COMMISSIONER OF FISH AND FISHERIES. 115 
above involved the careful tabulation of all the meter records, a tedi- 
ous operation involving a large amount of calculating. This work 
was completed in December. Upon discussing the results with com- 
petent physicists and engineers it seemed best, in order to avoid all 
possible sources of error, to continue the work for a short time during 
the summer of 1901. By making slight alterations in the apparatus 
it is hoped to reduce to a minimum some of the unavoidable errors. 
The work on the biology of the plankton algze of Lake Erie was 
continued by Dr. Julia W. Snow in the botanical laboratory of the Uni- 
versity of Michigan. Material collected at Put-in Bay was frequently 
forwarded to Dr. Snow in the living condition and was used in prepar- 
ing cultures. The results of Dr. Snow’s work during the summers 
of 1898, 1899, and 1900 have been embodied in a paper, with numerous 
colored figures, which is an important contribution to the subject. 
Mr. R. H. Pond continued his investigation on the source of nutri- 
tion in the larger aquatic plants. This work was carried on chiefly 
at Ann Arbor by means of aquarium experiments. Mr. Pond also 
visited Put-in Bay at intervals and there conducted experiments in 
which large numbers of aquatic plants were cultivated under various 
conditions. Briefly stated, Mr. Pond’s work shows that in the case 
of several species of the larger aquatic plants there is, contrary to 
the usual opinion, undoubted dependence on the soil for nutrition. 
In April, 1901, an investigation of the breeding habits of the stur- 
geon in the rivers of western Michigan was undertaken-by Prof. 8. O. 
Mast, of Hope College, Holland, Mich. <A study was made of the 
ascent of western Michigan rivers by this fish, with a view to deter- 
mining where fish might be obtained for artificial propagation. Mr. 
Mast collected a considerable body of facts by correspondence and 
made some observations in person. The observations show that the 
sturgeon still ascends these rivers (Kalamazoo, St. Joseph, Grand, and 
Manistee) in small numbers, but it is not apparent that artificial 
propagation on a profitable scale could be undertaken there. 
In May and June Professor Reighard maintained, under the auspices 
of the Commission, an observation camp on the Huron River, Michi- 
gan, for the purpose of studying the breeding habits of various fishes. 
Among the species to which special attention was given was the dog- 
fish (Amia calva), which was under constant observation from the 
time the young fish, attended by the males, left the nests in swarms 
until they had attained a length of 35 inches. The adult fish also 
came in for study. Other species which were studied in some detail 
were the common sun-fish (Hupomotis gibbosus), the bullhead (Amer- 
urus nebulosus), and the black bass (Jficropterus). 
The large collections of invertebrate animals of Lake Erie obtained 
since the beginning of the survey have been distributed as follows for 
study and report: Mollusks, to Mr. Bryant Walker, of Detroit; nemer- 
tine worms, to Dr. C. M. Child, of the University of Chicago; leeches 
and oligochtes, to Dr. J. P. Moore, of the University of Pennsylvania; 
