76 Transactions. 



the diseased fish were expected to he cured they and all other fish 

 in the river would be killed. On the 2 2d of March last I was 

 again favoured by Mr Fenton sending me two diseased Grayling 

 and a cut from a Salmon. The cut from the Salmon had no trace 

 of fungus. Skin and scales were all clean and perfect, but the 

 muscle below the skin for from uue-half to three-quarters of an 

 inch had that inflamed-looking appearance, and was swarming -with 

 Bacteria, while the muscle of normal colour was quite free from 

 them. Both of the Grayling were females, full of healthy-looking 

 i-oe : both had fungus on the same part — from the ventral fin 

 round behind the dorsal fin — and both had the same condition of 

 muscle that I have already described. One had heart, liver, and 

 all internal organs healthy, so far as I could judge, with a very 

 small quantity of digested food in the large intestine. The otlier 

 had an inflamed patch on the side of the stomach. Sections of 

 that part on examination were found full of Bacteria. Its liver 

 also was in the same diseased condition, and it had no trace 

 of food in it, and no doubt would very soon have died. I have 

 seen it stated that the act of spawning so weakened or lowered 

 the condition of the fish that they became a prey to the disease. 

 But that cannot be so, as I have seen at least three female fish full 

 of healthy-looking roe, seemingly ready for being deposited in the 

 spawning bed. I have given something like a description of the 

 disease as I have seen it ; and if the theory I have formed 

 regarding it is correct, the next point to be studied is its cause. 

 At present I am of opinion that the cause must be looked for in 

 the water by examining chemically, microscopically, and experi- 

 mentally, quantities of water taken from the river in the autumn 

 when it is very small, after a long absence of rain. 



