BACTERIAL DISEASE OF FRESH-WATER FISHES. 



273 



Experiment No. 1. — September 6 a number of buffalofish and crappie were seined 

 from a wire inclosure in the river (see fig. 258) where they had been held since Septem- 

 ber 2. The fish were in good condition and were divided into two lots before being 

 placed in aquaria well supplied with running water. Except for the copper-sulphate 

 treatment both lots were kept under as nearly identical conditions as possible. Sixteen 

 crappie and eight buffalofish were treated with a 1 to 1,000 solution of copper sulphate 

 for two minutes (water temperature 71 F.) before being placed in the aquarium. The 

 controls, 10 crappie and 8 buffalofish, were placed directly in an aquarium with- 

 out treatment. September S among the controls there were two crappie dying with 

 the disease, while most of the remaining fish showed considerable infection on the fins 

 and sides of the body. Among the treated fish, one buffalofish and two crappie 

 were slightly infected. At this time there was a very striking difference in appear- 

 ance in the two lots of fish. The untreated fish were nearly all in bad shape, with well- 

 developed lesions and considerable mucous on various parts of the body. On the other 

 hand, the treated fish appeared bright and clean, and those infected showed only 

 slightly developed lesions. September 9 two more crappie and one buffalofish were 

 found dead among the controls. There were no new infections among the treated fish 

 and one infected crappie was improving. September 10 there were one dead buffalo- 

 fish and one dead crappie among the controls. The treated lot were in good con- 

 dition, and those infected, with the exception of one crappie which died, were recovering. 

 Since there were no new infections and the slightly infected fish in both lots were 

 recovering, the experiment was discontinued on September 11. The treated lot at 

 this time was noticeably in better condition than the controls. 



Summary of Experiment No. i. 



Experiment No. 2. — September 13 a number of buffalofish and crappie were removed 

 from the same inclosure and treated as in the preceding experiment. Since the details 

 of the experiment do not differ in principle from the preceding, it will be sufficient to 

 summarize the results : 



Summary op Experiment No. 2. 



