plankton in Lake St. Clair is- relatively small. (2) The plankton is 

 distributed over Lake St. Clair vdth great uniformity. (3) There is 

 much more plankton in the surface stratum of water than in any deeper 

 layer of equal volume. (U) There is about three times as much plankton 

 in Lake Erie in the neighborhood of Put-in-Bay Islands, as in Lake 

 St. Clair." 



In 18914, Ward and his associates made a study of the plankton of 

 Lake Michigan in the Traverse Bay region. (Ward, 1895 and I896) . The 

 methods employed were almost identical with those employed by Reighard 

 in Lake St. Clair. Ward found that the mean volume of plankton at I8 

 stations was 3*69 cubic centimeters per cubic meter. This amount was 

 not far different from the mean for Lake St, Clair as reported by 

 Reighcird. However, Ward pointed out that the mean volume for hauls in 

 Lake Michigan at depths similar to those in Lake St, Clair (1,5 to 

 5,6 meters) was 6,39 cubic centimeters per cubic meter, or more than 

 twice the mean for Lake St, Clair, In Lake Michigan the total amount 

 of plankton increased with greater depth, but the amount per unit 

 volume decreased. There was no evidence of swarms of the total plankton. 

 Investigation of vertical distribution showed that the volume of 

 plankton per unit volume of water was much greater in the upper two 

 meters than in lower strata. The deepest stratum was almost devoid of 

 plankton. 



In 1898 the United States Fish Conmission established a biolog- 

 ical laboratory at Put-in-Bay, Ohio (Smith, I898), The laboratory was 

 under the direction of Professor J, E. Reighard, and a number of other 

 investigators were on the staff. For a brief account of the work carried 

 on here, the reader may refer to the reports of the Commissioner of Fish 

 and Fisheries for the years ending June 30, 1899, 1900, 1901 and 1902, 

 Some quantitative studies of the plankton were made, but the results have 

 never appeared in print. It was almost 30 years before another party of 

 investigators undertook a quantitative study of the plankton of the 

 Great Lakes, 



In the meantime the only quantitative results published were 

 those of Whipple (Leighton, 1907) in Lake Michigan at Chicago; Stehle 

 (1923) on the protozoa of the surface waters near Put-in-Bayj and Eddy 

 (1927) on the littoral plankton of the southern part of Lake Michigan, 

 Whipple's results were too fragmentary to justify discussion here, Stehle 

 counted the plankton protozoa in measured samples of surface water taken 

 in the harbor of Put-in-Bay, in Terwilliger's Pond, and in the open lake. 

 Only 18 forms were taken in the open lake and their abundance was never 



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