VI 



fish when attacked on the head are called " salmon with white night- 

 caps." There is hardly any part of the body of the fish which is 

 not liable to be attacked by this fungus ; but the parts first affected 

 are the softer portions of the body which have no scales. Thus, 

 for instance, the nose and the back of the head are generally first 

 attacked. The next part attacked is usually the tail. It is, 

 however, on the tail, the dorsal fin, and the pectoral fins that the 

 fungus is found, to a greater or less extent, according to the 

 virulence of the disease. In bad cases, masses of fungus are also 

 found on the inside of the palate.* It is noticeable that as the 

 disease advances it attacks the delicate structure of the gills, and, 

 forming upon them a deposit not unlike glue, affects the respira- 

 tion, if it does not entirely put an end to the life of the fish by 

 suffocation. 



The internal viscera of diseased fish do not, in general, materially 

 differ from the internal viscera of undiseased fish in a similar stage of 

 existence, though in some cases the livers of diseased fish are pale 

 and break down easily under the finger. 



The brains of diseased fish have been occasionally found in a state 

 of inflammation, but this probably arises from the irritation caused 

 by the fungus eating through the skin into the bone of the 

 skull. 



The symptoms affecting live fish do not seem to have been 

 observed so carefully as the appearances on the dead fish ; it is 

 certain that the presence of the fungus causes a very great 

 amount of irritation and probably pain to the fish, as they are 

 seen throwing themselves about as though in great agony, and 

 when exhausted swimming about in a helpless manner on the 

 surface of the water. Thus Mr. Stoddart (Appendix, p. 43) 

 informed us there was a sort of rabies among the fish. " They 

 " were rushing about as if distracted with pain, skimming along 

 " the surface of the water." 



As regards the external appearance of the disease we select the 

 following passages out of the evidence : — 



" The fungus had eaten into the flesh, beginning generally at the 

 « head." 



" The fish were covered with fungus from head to tail. The 

 " intestines were in perfect order, and the flesh was firm and rich." 



" The first stage in old fish is a white spot on the frontal bone." 



" The fish had spots generally above the dorsal fin, on the head, 

 " and near the side. The spots were as large as a half-crown on 

 " the back of the head. The sores were covered with fungus." 



" The fish had white spots about the head, fins, and tail. The 

 " fungus grows on the white spots, and rubs off like scurf." 



" The whole head of the fish is covered, like a white night-cap." 



" Noticed a quantity of fungus near the nose ; and the head, the 

 " back fins, and tail had almost rotted away." 



" The disease begins at the head and near the eyes, top of tail, 

 " and back fin. Has seen fish with the eyes almost out of them." 



* A plate, taken from a photograph of two diseased fish, forms the frontispiece of 

 this Eeport. 



