224 How to obtain it. 



dangerous to other fish. I have seen fish eat pieces of fungus 

 without apparently receiving any harm, and on introducing a con- 

 siderable growth of the plant into an aquarium, none of the fish 

 contained therein were attacked, nor did they suffer apparently 

 the slightest inconvenience from the presence of the pest. 



That fish in a sound healthy state seem to be comparatively 

 safe from its attacks, under ordinary circumstances, secerns to be 

 : tolerably certain. What those extraordinary circumstances are, 

 that tend to render fish at times so liable to be attacked, require a 

 .great deal of investigation. We know a good deal about the fungus 

 itself indeed we are by this time well acquainted with its life 

 history but we do not know all we might know about the salmon. 

 There is a " missing link " in the life history of that fish that 

 leaves us still in ignorance, and when our knowledge is sufficiently 

 increased, we may be able to apply some remedy for the great 

 scourge which has ravaged our rivers, as well as those of other 

 countries. 



After trying a great many experiments upon fish of one kind 

 or another, I am satisfied that there are several distinct conditions 

 under which the fungus exists upon their bodies. The result of 

 my experiments leads me to the conclusion that, as a rule, fish 

 that are strong and vigorous in constitution, and at the same time 

 sound in body, are comparatively safe from the attacks of fungus. 

 But there are many modifications of this rule. I will refer to 

 -some of them : 



1st. Take a strong healthy fish that has got wounded on the body, or on a 

 fin. So long as the wound remains clean fungus will not necessarily 

 grow, but sooner or later little bits of flesh or skin become dead, and 

 decay sets in. Then the fungus grows upon them. This I have witnessed 

 repeatedly, and also that under such circumstances fungus will remain 

 for a long time without spreading. It is quite easy to remove it, and 

 while it exists the fish does not seem to be any the worse for its 

 presence. 



2nd. Fungus from some exceptional cause or other will attack the tail 

 or other part of the fish to a considerable extent, say a patch as large 

 as a half-crown. The rest of the body remains in an apparently 

 healthy state, and the patch of fungus goes on spreading over it from 

 the one centre only until the fish is killed, but no other fungoid growth 

 has been commenced upon it, and the uncovered portioned of the skin 

 -apparently remains in perfect health. 



