The report is based principally on data obtained in the seasons of 1929 

 and 1930, From the data of 1928, certain ones have been selected for in- 

 clusion. Selection was based primarily on the possibility of fitting the 

 data intj the plan of presentation for those of 1929 and 1930. No data of 

 1927 have been included. Those of 1926 have been treated as published data, 

 and where possible, introduced to supplement the data of later years. 



In preparing the report, it appeared advisable to review the scientific 

 literature on all of the Great Lakes, rather than that on Lake Erie alone. 

 Although the lakes other than Lake Erie are almost entirely unkno^im from the 

 point of view of modern limnology, there are a large number cf papers which 

 would be of value in planning future investigations. Since the literature 

 is widely scattered, and, in some cases, difficult of access, it seemed de- 

 sirable to review it in this report. Accordingly, many of the chapters or 

 sections of chapters contain a brief account of previous investigations in 

 the Great Lakes. In some cases the review consists merely of a citation of 

 literature; in other cases results were introduced. No attempt was made to 

 cite all of the literature encountered. V/here possible and desirable, 

 reference was made to reports which contain extensive literature lists. 

 For example, the reader will be referred to Horton and Grunsky (1927) for 

 details and literature concerning hydrology, and to Leverett and Taylor 

 (1911?) for geology. In this way it was possible to attain a degree of 

 completeness without undue increase in the size of the report. It is quite 

 probable that some papers have escaped notice, but it is hoped that the 

 reader will find reference to all of those of importance by use of "key 

 references", such as those mentioned above. Papers on ichthyology and 

 fishery science have been included only when they had immediate bearing on 

 the problem in hand. Forthcoming reports will deal with these subjects in 

 detail. None of the several papers on limnological investigations in the 

 Great Lakes published since 1933 is included in the bibliography, and the 

 list for 1933 is probably incomplete. 



Acknowledgments 



In 1926, the survey was in charge of Dr. R. C. Osburn, Director of the 

 Franz Theodore Stone Laboratory, and he was closely associated with the work 

 in following years. After 1926, the investigation v;as londer the general -di- 

 rection of Mr. E. L. hlckliff. Chief of the Bureau of Scientific Research, 

 Ohio Division of Conservation. Participation of the U. S. Bureau of Fisheries 

 in 1929 and afterward was under the direction of Dr. John Van Oosten, In 

 Charge of Great Lakes Fishery Investigations. It is a pleasure to acknowledge 

 the essential part played in the investigation by these men. 



In an investigation of the kind reported here, covering five seasons of 

 field study and several categories of aquatic biology, it is only natural 

 that those intimately associated with the work would seek aid from others in 

 a position to render it. The number of persons who have made contributions 

 cf general or professional nature is great. A large measure of the success of 



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