132 BOARD OF AGRICULTURE. 



like be owing to the difference in the habits and constitution of 

 similar fishes in the two hemispheres. 



Tliere is another point that is of great importance. Fishes 

 breed at very different seasons, and require, during the time 

 necessary for the eggs to hatch, very different conditions. There 

 is one entire family of fish, that of the Salmonoids, as naturalists 

 call them, including the Salmonidce, which all breed in the cold 

 season of the year. They require very cold water to be hatched. 

 Here we must accept ideas entirely different from those with 

 which we are familiar. When we would hatch the eggs of our 

 hens or of other birds, we know that we must submit those eggs 

 to an increased temperature. The hen sits in feverish heat 

 upon the egg, and by that heat she warms the yolk, the germ is 

 developed, the chick grows, and is finally hatched. If you were 

 to submit the eggs of the trout to a higher temperature than 

 that of the water in this cold season, your eggs would die at 

 once. It must be remembered that the temperature most favor- 

 able for the raising of trout's eggs, is about 40° Fahrenheit, and 

 rather below than above. They may stand a temperature down 

 to 32 ; they may even be surrounded by ice, frozen in, and yet 

 not die ; and if you expose them to any warmer temperature, 

 you are sure to kill your whole brood. 



Here is an important point to remember, in connection with 

 the raising of that particular class of fishes ; and all the mem- 

 bers of this family are in the same predicament. To this family 

 belong, in the first place, the salmon, then lake trout, then brook 

 trout, and all the different kinds of brook trout. Moreover, 

 the white-fish of the great lakes belong to this family. It looks 

 very differently in its external appearance, and yet it has all the 

 organic or structural character of the trout ; and, like the trout, 

 it breeds in this late season of the year, and its young are 

 hatched under the influence of a cold temperature. I have 

 myself made experiments upon these white-fish ; not the kind 

 which we have in our lakes, but the kind which is quite common 

 in the lakes of Switzerland. Some thirty years ago and more, 

 for physiological purposes, I raised some of those fishes, and I 

 frequently, exposing them in a cold room, found them in the 

 morning frozen up in the wash-bowl in which I kept them ; and 

 yet they would stand that perfectly well, and if the temperature 

 was never raised above 40°, I was sure to carry those young 



