How to obtain it. 223 
sealed vessel, but it will not grow in the open air. When the 
water is low in our rivers and fish lie long in the pools, it often 
happens that the “fungus” assumes an epidemic form. Therefore 
if we can increase the supply of water, by producing an artificial 
spate, the fish are helped to reach the sea, and as sea water has 
been ascertained to be fatal to it, the benefit is apparent. 
Saprolegnia is a cryptogamic plant, belonging to the group 
Thallophytes, and it occupies a position in that group between 
Stphonee of the Alew and Phycomycetes of the Fungi. At one time 
it was a disputed point whether it belonged to the animal or 
vegetable kingdom, but there is now, I think, no doubt about 
that. The only doubt that remains seems to be its exact position 
as a cryptogam. When seen upon a salmon or a trout it has a 
woolly appearance, and often occurs in patches the size of a 
shilling or a half-crown. Sometimes it covers the whole of the 
head of a fish, whilst in others it takes possession of the tail or of 
the back, or grows in a small tuft from one or more of the fins. 
If we examine this woolly-looking mass through a strong 
magnifying glass, we shall find that it consists, first of all, of a 
matted-looking mass of filaments, lying comparatively flat upon 
the body of the fish. This practically constitutes the root, and is 
known as the mycelium. From this root, or mycelium, rise a 
multitude of filaments or stems, called Ayp/a@, each one of which 
consists of a hollow tube, and a great many of these tubes have 
their terminations enlarged, and assume a somewhat club-shaped 
form. This club-shaped vessel is a zoosporangium and is found 
on examination, as well as the tubes, to be full of minute seeds or 
zoospores. These, when ripe, are rapidly expelled from the zoo- 
Sporangium, or seed vessel, and have the means of locomotion, 
moving about in the water by means of their two c/a, which may 
almost be likened to a pair of oars. 
Until the plant is ripe, and begins to give off its seeds, there 
is not much danger of infection, and in its earlier stages it is 
easily destroyed by permanganate of potash or carbolic acid. To 
kill and bury every fish that can be got out of a river with any 
fungus upon it is a great mistake, and yet I have known this to be 
done. A great many of the fish so destroyed might have been 
saved, the fungus upon them not being at the time particularly 
