490 KEPOET OF COMMISSIONER OF FISH AND FISHERIES. 



ress wliicli this braucli of industry lias made of later years. The labors 

 of Eemy and Gchin, and those of M. de Qiiatrefages, of M. Coste and 

 M. Millet, represent the present state of this department of agricultural 

 science. To them belongs the honor of having regulated and perfected 

 the methods, and of having determined the basis of a cultivation before 

 A'ery vague and precarious. 



III. 



The processes which we have analyzed are not all equally adapted for 

 easy and profitable application. It remains then to compare the respec- 

 tive advantages of them, to determine the combined measures which 

 pisciculturists ought to adopt. 



The first care to be taken when it is desired to stock a river or pond 

 is to learn what species of fish will best adapt themselves to the circum- 

 stances whicli happen to be united there. To escape the danger of cer- 

 tain failure, it is first of all necessary that the nature, the ordinary tem- 

 perature, the depth, and the various qualities of the waters to be en- 

 riched should agree with the instincts, habits, and way of life of the 

 animals to be developed there. These recommendations are found in 

 all books upon the subject, but cannot be too often repeated. It is most 

 certainly from the neglect of these proprieties, and want of appreciation 

 of them, that certain pisciculturists have seen their attempts miscarry 

 when they were otherwise skillfully executed. 



When, therefore, the ground, as it were, has been studied in advance, 

 and it has been determined what sort of fish has the best chance of 

 prospering there, the individuals necessary for the multiplication of the 

 chosen species should hot be procured except at the very season of spawn- 

 ing, since very often the products are spoiled in the bodies of fishes 

 which are condemned to close captivity. This inconvenience does not 

 present itself if the animals can be placed in reserve in inclosures near 

 the rivers or ponds in which they have been caught. Otherwise they 

 may be held by a cord in the same places where they have lived. It 

 is important, before effecting the fecundation, to pay attention to the 

 temperature of the water, which has so great an influence upon the 

 properties of the milt, as M. de Quatrefages has so clearly shown, and 

 probably also upon the vitality of the egg itself. Although M. Vogt 

 has seen the eggs of the palee* prosper after they had been taken in ice, 

 this extreme cold is generally sufficient to destroy them. 



The gathering of the male and female elements should be made on 

 diflerent occasions and in several days. It seems useful, in many cases, 

 to guard the products from all exterior influences, and not to take them 

 from their natural medium. For this purpose a male and a female are 

 taken and inclined near each other at the surface of the water. They 

 are then bent gently upward, which produces a strong contraction, and 



*A species of wbite-fisb {Corefjonus paJni.) 



