224 Flow 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, seems 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 :— 
ist.—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 
portion of the skin apparently remains in perfect health. 
