6 
decaying vegetation, retains the rain water and prevents it 
from rushing to the rivers and the sea, while it gives it off 
to these slowly and steadily. It acts like a great sieve and 
retains the fine particles of the soil, which the influence of 
the air and sun, the frost and rain, and the action of the 
numberless roots have decomposed, thereby fertilising the 
land and forming a layer of mould or humus, in which insects, 
worms, larve, and other animalcules live and breed. 
In his most interesting paper on fish diseases, Prof. 
Huxley said that drought or flood did not seem to affect 
the Saprolegnea, but that a steady flow was beneficial to 
the fish. 
Mr. Wilmot, in the following discussion, pointed out that 
the disease nearly always appeared where the regularity of 
the supply of water had been disturbed by the destruction 
of the forests. 
I presume, therefore, that both these learned and prac- 
tical gentlemen will agree with me in the importance of 
the forest protection as a means of preserving the health of 
the fishes. 
The branchlets, leaves, decaying and decayed vegetation, 
produce a vast amount of nourishment for the fish, and one 
most agreeable to them. Each breeze drops into the 
water numberless grubs, caterpillars, beetles, flies, and 
other insects, the food most relished by the fishes, while from 
the banks and roots worms and grubs are constantly sup- 
plying them with delicacies. 
The shade of the overhanging trees is also agreeable to 
the fish, and one needs only place a board in a stream and 
see the fish gather underneath it to be convinced of this. 
We all know that a shady deep pool is a good place in 
which to seek for fish, and have often observed the predilec- 
tion fish have for the shady side of a stream. But not 
