The possible effect of poisonous chemicals on the fishes of 

 the lake vdll be considered in later pages (page 303). 



Chloride content of Lake Erie 



The ainount of chlorine as chloride in Lake Erie is hi(;h as 

 compared with the upper lakes. According to analyses reported by- 

 Dole (1909), the mean for Lake Erie at Buffalo in I906-I907 was 8.7 

 parts per million, as compared with 1.1 for Lake Superior, 2,7 for 

 Lake Michigan, and 2.6 for Lake Huron. The mean for the Island Section of 

 Lake Erie in July, August, and September, 1930, was 10,3, which agrees 

 closely with the mean at Cleveland for the same months of I9IO-I9II as 

 reported by Jackson (1912), 



Domestic sewage and certain kinds of trade wastes contain 

 much sodium chloride, and when the normal content of a lake is known, 

 chloride is a valuable index of the degree of pollution. Jackson 

 (1912, page Li3) stated that the high chloride at Cleveland had no 

 sanitary significance because of the inflow of salt from salt works 

 and natrral deposits, A review of the. literature leaves no doubt that 

 Jackson's conclusion should apply to the lake as a whole. References 

 of special value in this connection are: Sherzer (I9OO and 1913), 

 Kellogg (1917, p. 'OU and 192$, p. ijB), Fuller (190$), Ohio State 

 Board of Health (1899), Foulk (192$). 



The phytoplankton of .Vestern Lake Erie, 



Introduction 



Previous investigations in the Great Lakes-' 



The earliest investigations of the algae and protozoa of the 

 Great Lakes were made on material obtained from municipal water supplies. 

 By taking samples from the tap-water periodically, it was possible to 

 follow seasonal changes in the plankton of the lakes. 



^The large aquatic plants were not studied. The following papers on 

 large aquatics of the Great Lakes were encountered in the literature: 

 Campbell (I8B6) Pieters (I89U and 1901), Thompson (I896), Moseley (1899), 

 Pond (1905), MacClement (19l5), Klugh (1915), and Muenscher (1929 and 

 1932). See also Miller's bibliography of Ohio botany (Miller, 1933). 



139 



