164 Wisconsin Academy of Sciences, Arts, and Letters. 



Professor Andrews and IMr. Blatchford, and pnt in a day's work 

 dredging on Lake Michigan in June, 1870. The result was the 

 collection of a considerable number of animals. Especial im- 

 portance was attached to the discovery of a Triglopsis and a 

 Mysis, as they are marine genera, and their presence was sup- 

 posed to indicate a former direct connection of Lake Michigan 

 with the ocean. 



In 1874 Professor Smith published a paper on the "Inverte- 

 brate Fauna of Lake Superior," reporting the existence of the 

 same Crustacea in Lake Superior which Dr. Hoy had found in 

 Lake Michigan. The My sis there, however, occurs in somewhat 

 shallow w^ater as well as in the greater depths. In both lakes it 

 forms an important — perhaps the most important — constituent 

 of the food of the white fish and lake trout. As I was located 

 near a lake of considerable depth, a depth reputed to be any- 

 where between 400 feet and iniinitv, it occurred to me that I 

 had an opportunity to carry out similar researches. 



My own work on lakes, then, originated in a desire to know 

 more about the abyssal animals. I soon found, hoAvever, that 

 the problem was a serious and complicated one, involving a com- 

 plete faunistic study of the lake. I was fortunate in finding on 

 the bottom of Green Lake the same My sis, which makes its home 

 in Lake Michigan. These animals have not been definitely re- 

 ported from any other lake in the United States, although Mysis 

 is said to live in a lake in E^cav York connected with the St. Law- 

 rence. Here was a pretty problem in animal distribution. 

 How did these animals make their wav into Green Lake-? Wa3 

 it by way of the Great Lakes, or did they come at some time by 

 a connection through the Mississippi Valley? I could not tell, 

 and I cannot today, for it becomes a problem for the geologist 

 rather than the zoologist. With this as a starting point I 

 attacked the problem of lake fauna?, and the battle is still in pro- 

 gress with no indications of a conclusion of hostilities for many 

 years to come. 



During the decade in which I have been interested in limnol- 

 ogy there has been a very considerable advance in our knowledge 

 of the subject, and it will be my attempt tonight to siunmarize 

 this knowledge, and make as clear a statement as I can in the 



