109 



FISH FUNGUS AT CALEDONIA. 



BY PROF. CHARLES WRIGHT DODGE. 



Department of Biology, 



University of Rochester, 



Rochester, N. \.,Junc nth, i8g^. 



Frank J. Amsden, Esq., 

 Rochester. 

 My Dear Sir :— 



The object of the experiments on the growth of 

 the fungus (Saprolegnia) infesting the trout at Caledo- 

 nia is to find a means of preventing, or at least retard- 

 ing, the development of the fungus without at the same 

 time killing the fish. It seems very evident that the 

 whole body of water in Spring Creek contains the 

 spores, as well as the growing plants, of the fungus. 

 A single mature plant will produce many thousand 

 spores under suitable conditions. Each spore is capa- 

 ble of producing another plant which in two days or 

 less reaches maturity and, consequently, produces its 

 quota of spores. Each spore is provided with a pair 

 of delicate thread-shaped motile organs, by means of 

 which it swims about in the water, like an " animalcule," 

 until it finds a favorable place to grow. It then at- 

 taches itself to the substratum, which may be the dead 

 and decaying, or frequently the living, body of a fish, 

 snail, frog, insect, or some plant in the water. The 



