The Fungus of Salmon Disease. 57 



rub themselves against stones to try and detach the fungus, but 

 such efforts, of course, only cause wounds and injury to the 

 epidermis, while opening fresh ground for the disease to pene- 

 trate, though in the case of open wounds there are probably 

 other organisms besides the fungus that can hasten the end. 



The fish are liable to be attacked all over the body, but the 

 back or the head, and the region of adipose fin (where they 

 are not protected by scales), are the worst places. I have seen 

 fishes quite blind, and with their bodies almost covered with 

 the growth ; but it is the usual practice to snare the fish, and 

 remove them from the water as soon as they are seen to be 

 badly diseased. 



The time that elapses before a fish can be actually killed by 

 the fungus varies according to the season of the year, and the 

 rapidity with which the fungus grows. In winter it is not 

 unusual for a fish to live for ten days or a fortnight with the 

 disease growing all the time, but in summer death will follow 

 in half that time. 



Some idea of the injury that can be caused to rivers may be 

 gained from the published statistics of the Fishery Inspectors, 

 where we learn that from the River Esk as many as 350 dead 

 salmon were removed in three days ; while in several other 

 rivers the disease has been known to kill in a month or two as 

 many salmon as would equal half the take of an ordinary fair 

 season. 



The disease, though not doing as much injury now as for- 

 merly, is still prevalent in many of the same rivers, and others 

 are being added to their list every year. It often disappears 

 for a year or two, only to break out again nearly as badly as 

 ever in the same locality, and the reason why the fish should 

 suffer so terribly now, when the disease in its present epidemic 

 form was unknown a few years ago, has not, I think, been 

 satisfactorily accounted for. As long as this is the case, its dis- 

 appearance cannot wich certainty be assured ; neither can we 

 feel confident that it will not break out again. 



The origin of the salmon disease is (as is the case with all 



