470 AMERICAN ANGLER'S BOOK 



thumb upon the belly and its fingers on the back and sides, is 

 passed liked z ring lightly backwards and forwards, to bring 

 the eggs near the opening through which they are passed. 

 The male fish is then to be operated on in the same way, 

 and the milt expressed ; the manipulation causing the expul- 

 sion of only so much of the oya and milt as may be perfectly 

 mature. For, as will be seen by the observations quoted 

 from " The Book of the Salmon," in a previous chapter, all 

 the roe and milt does not ripen at once, but that the time of 

 laying the eggs and fecundating them in a natural way, 

 extends over a period of ten days or more. Hence the 

 necessity of a tank supplied with running water, as a tempo- 

 rary residence for the breeding fish, that the ova and milt 

 may be expressed as it matures. 



The appearance of all the eggs, whether fecundated or not, 

 is much changed in the course of a few minutes. They are 

 at first more opaque than they were when discharged from 

 the fish, and then assume their transparency. M. Ooste says 

 it is only after some days that the barren eggs can be distin- 

 guished from the fecundated, and that they deteriorate rapidly 

 become more and more opaque, turn white or else preserve 

 their transparency, but show no interior change. Taking 

 the spawn and milt from the fish is a matter of so much 

 interest, that I quote his remarks at length. 



" If the eggs are hard, and already free from the membrane 

 of the ovaries, the slightest pressure suffices to expel them, 

 and under this pressure the abdomen is emptied without 

 injury to the female operated upon ; for the following year 

 she will become as fruitful as if she had spawned naturally, 

 as we have often had occasion to observe at the establishment 

 at Huningen. 



" If, on the contrary, it appears that a greater degree of 

 pressure is necessary to bring out the eggs, we may be sure 



