APPENDIX I. 



A NEW DISCOVERY.— CURE FOR FUNGUS. 



Salt a Cure for Microscopic Parasites on Trout. 



IN the spring of 1872 I began some microscopic exami- 

 nations of the parasites on large and small trout, which 

 led to the discovery of a cure for what has hitherto been 

 thought to be incurable disorder. 



It is well known that when trout become injured or un- 

 healthy a fungoid growth appears in blotches over the sur- 

 face of their backs, usually terminating in fatal results in a 

 few days. 



It has hitherto been supposed, I believe, that the fungus 

 eats into the tissues of the fish, and destroys it. The mi- 

 croscope revealed, however, that it was not the fungus that 

 penetrated into the fish, but a multitude of microscopic 

 worms of the shape and appearance given on page 258. 

 The worms are never found in the upper parts of the fun- 

 gus, but just below at the roots, or where the fungus joins 

 on to the surface of the skin. Here between the roots of 

 the fungus and the body of the fish are found hundreds of 

 these creatures incessantly in motion and apparently eat- 

 ing vigorously. They are about -^^ of an inch in length 

 and 2^0 o^ ^^ i"c^ ^^ diameter, and are provided with a 

 mouth at one extremity and at the other with about twenty 

 claw-like appendages for fastening on to the fish on which 

 they feed. They are continually eating into the tissues of 

 the fish, and the twenty tentacles enable them to fasten on 

 so tightly that the fish cannot shake them off. These para- 

 sites appear to live on the flesh of the fish, and the fungus 



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