220 VICTOR E. SHELFORD AND W. C. ALLEE 



two Lepomis taken from the Fox River at Cary, Illinois, October 

 21, were included. The Ameiurus, Abramis, and Umbra came 

 from a pond at Pine, Indiana, November 11. This stock was 

 divided and one part was put in a standing-water aquarium and 

 supplied with boiled water from time to time. This part of the 

 stock will be referred to as the 'low oxygen stock.' All other 

 fish were kept in aquaria supplied with running water from the 

 tap. During the period of experimentation, the fish kept in 

 good condition, with low mortality. 



Most of the deaths were due to fungus attacking slight injuries 

 or lesions, due to gas bubbles or handling. The fish fed largely 

 upon small minnows which were present in the aquaria in large 

 numbers; also upon fish foods and pieces of fresh water mussel. 

 After December 1 the stock of fish was put into a large basement 

 tank, supplied by the overflow from a large artificial pond on the 

 campus. This water contained plankton and occasional inverte- 

 brates. The fish were kept all winter and noticeable mortality 

 did not begin until April. 



2. BEHAVIOR AND PHYSIOLOGY OF FISHES 



Fishes usually remain active all winter (Abbott '75) appar- 

 ently carrying on their regular activities as in warmer weather. 

 The temperature of streams and of larger bodies of water prob- 

 ably does not fall below 4 to 6°C. before the end of December. 

 Our experiments were performed in November and December, 

 only a few being conducted in January. The behavior of fishes 

 in autumn is not modified by the breeding activities and fishes 

 may be brought to the laboratory in very large numbers without 

 mortality and kept alive. 



In mode of locomotion the fishes studied fall into two main 

 classes. The first class comprises those that rest on the bottom 

 much of the time, swimming by darts; this type includes Boleo- 

 soma, Etheostoma, and young Catostomus, the latter being some- 

 what more like the other fishes. The second class is made up 

 of fishes that swim at a uniform rate, starting slowly. Umbra 

 Hypobsis, and Ameiurus often rest upon the bottom; the other 

 species do so rarely. 



