THE NEW ART OF BREEDING FISH. 61 



and more opaque, turn white, or else preserve 

 their transparency, but show no interior change. I 

 have seen numbers of eggs of salmon, trout, ombre, 

 and pike appear thus up to the moment when other 

 eggs preserved with them, of the same spawn, and 

 submitted to the action of the same milt, had come 

 to maturity and hatched. 



On the other hand, in eggs vivified with the fe- 

 cundating molecules, one may see after a time, which 

 varies according to the species and to the tempera- 

 ture of the water, on the interior globe a line, which 

 covers about a quarter of its circumference. This 

 line, which seems whitish when the eggs are on a 

 dark ground, or opaque when they are held up to the 

 light (in the manner in which our farmers examine 

 hens' eggs), is the origin of the foetus, and represents 

 the spinal column. As this line increases in size, 

 one end of it grows out to a point to form a tail, and 

 the other extends in the form of a spatula. This 

 last corresponds to the embryo's head, and of this 

 there is soon no doubt, for the eyes now appear, two 

 points of a blackish brown, easily distinguished, and 

 forming nearly two thirds of the whole mass of the 

 head. As each day developes its form, the young 

 fish may be seen under the shell or membrane, 

 stretching itself, and drawing itself up, and wagging 

 its tail. When hatching time comes, these move- 

 ments, the probable object of which is to weaken or 

 tear the shell, become more active. With salmon 

 and trout there is another sign of the approach of 



