MANUAL, OF FISH-CULTURE. 17 



is a decided loss of fertilizing power. The ege:s do iiQt suffer so quickly 

 from immersion in water. The absorbing property M'hicli they possess 

 when they first leave the parent fish, and which attracts to the 

 micropyle the spermatozoa, lasts several minutes, but it is not prudent 

 t() leave the eggs in the water a moment longer than is necessary before 

 adding the milt. 



The addition of the water is not essential to a good impregnation; 

 in some instances better results are secured without the use of water 

 and, after all, if the main object is secured, of bringing the milt and 

 the eggs together with the slightest jiossible delay after they leave the 

 fish, it makes very little difference whether water is used or not. 

 The milt retains its fertilizing power several days when kept from air 

 and water, and impregnation can be effected between fishes widely 

 separated by merely forwarding the milt properly sealed. At Baird 

 impregnation by the dry method, which has always been followed there, 

 has resulted in the fertilization of about 90 per cent of the eggs so treated. 



The Russian or dry method of impregnating eggs consists simply in 

 taking both the eggs and the milt in a dry pan. It may be urged as 

 an objection to this method that the eggs will be injured by striking 

 against the dry pan, but it is a fact that although the same eggs would 

 be destroyed by the concussion a week afterwards, or even twenty-four 

 hours afterwards, they do not suffer in the least from it at the moment 

 of extrusion from the fish. 



It was at one time considered an important question whether the 

 eggs or milt shoidd be taken first, but with the dry method it makes 

 no difference, as, either way, both eggs and milt remain operative long 

 enough for all practical purposes of impregnation. 



Various methods of treating the eggs in the pan after impregnation 

 has taken place have been tried, and all apparently with about the 

 same results. Some operators leave the eggs in the pans as first taken 

 with the milt for two or three minutes and then add water, after which 

 they are left to stand in the pan until they separate, when they are 

 washed clean, taken to the hatching-house, and placed in the troughs. 

 Others pour the contents of the several pans — eggs, milt, and all — into 

 a large can, after they have remained in the pans just long enough to 

 become im])regnated. When the eggs separate the contents of the can 

 are poured into the hatching-troughs just as they are, tru&ting to the 

 current in the troughs to wash the milt from the eggs. Where the 

 water supply is scant and the current sluggish in the trays, the best 

 method is to wash the milt thoroughly from the eggs before placing 

 them in the hatching- trays, as the milt will foul the waier if it remains 

 in the troughs. 



The methods employed in taking and fertilizing eggs at Clackamas 

 station are as follows: The female fish to be operated upon is taken 

 from a floating pen and placed in the spawning-box or "straight- 

 jacket''; a male fish is then caught and tied with a small rope aBOund 



r. C. R. 1897 2 



