74 Tramactinns. 



this case I find embedded and moving amongst the striated muscle 

 fibre of the fish ; and when by pressure or otherwise they are 

 forced into the siu-ronnding fluid, they have a power of motion, 

 moving mostly in a sort of circular direction. In some fish that I 

 have examined I observed that the muscle was almost detached 

 from the strong fibro-muscle layer of the skin, and the muscle 

 fibres of that layer were not adhering together as in their natural 

 state, and could be separated from each other like threads by the 

 needle. Whether the diseased condition of that [lart of the skin 

 was caused by the state of the muscle immediately below it or by 

 the fungus on its surface I am not in a position to say. By looking 

 at the very rough drawing of a transverse section of Salmon skin 

 made by the Camera Lucida, you will observe a dark layer mai'ked 

 "opaque muscle layer." That is the fibro muscle layer of the skin 

 that I have been alluding to, and to which is attached the true 

 muscle of the fish ; and should the fish live long enough, ulcera- 

 tion of those afiected parts must take place. As I did most of 

 this work in the winter, when the frost was so hard, I took 

 advantage of it to freeze parts of fish in the section instrument, 

 and by this means I got some capital sections of fungus, scales, 

 skin, and muscle. I j^reserved one of those sections, which is a 

 veiy fine one, showing the forms of the Bacteria still in and 

 around the muscle. After examining a number of fish, and finding 

 the conditions alike in each, I then began to speculate a little as 

 to the nature of the disease I have just described, and the idea at 

 once suggested itself, after what I had seen, that the disease was 

 located in the muscle of the fish ; and I also have some idea that 

 when it is really known it will be found to commence in the 

 blood, caused either by the food they eat or by some deleterious 

 solution in the water which passes through tlie gills, and that the 

 unhealthy, decaying fluid or matter, which will naturally pass ofi" 

 from those Bactei-ia and exude through the pores of the skin, 

 forms a healthy and proper nidus for the germination of the 

 Zoospores of the fungus, which, as I have shewn you, must 

 be in those affected rivers in myi-iads. Now, let us look for a 

 little at what authorities say on the subject in support of my 

 theory. I have been told by persons having an aquarium that 

 previous to the gi-owth of the fungus on a fish it exhibits signs of 

 indisposition. Then Dr Carpenter says, when speaking of fungi, 

 " thei-e are various diseased conditions of the human skin and 

 mucus membranes, in which there is a combination of fungoid 



