FISH CULTURE. 249 



impreguatiou being strongest when the egg is first exposed, and weakest 

 toward the end of the period. 



Second. The milt appeared to he composed of microscopic animal 

 forms, inclosed or swimming in a whitish fluid. If this iiuid was re- 

 tained in the form in which it issued from the fish, the appearance of 

 life was continued for a considerable period ; but if the milt was diluted 

 with water all signs of life were destroyed in a very brief time. If, then, 

 both the egg and the milt could be kept from contact with the water 

 until they were mixed together, he thought the chances of impregnation 

 would be very much increased. Accordingly, having taken his eggs first 

 on a dry plate, he mixed with them the milt, and found that nearly all 

 his eggs were impregnated. And this process, or one very nearly re- 

 sembling it, has been used with great success by the fish breeders of 

 this country. 



'Now, a few words about this discovery. In the first place there can 

 be in practice no such thing as dry impregnation ; because more or less 

 water will always fall from the fish into the pan or plate, and it is hardly 

 practicable to wipe each fish dry with a towel before squeezing. Second, 

 a quantity of eggs, which will cover the bottom of a pan will absoid 

 no more water from a pan full of water than from a pan only one-half, 

 or one- quarter, or one-twentieth full. Third, the milt will die just as 

 soon in a little water as in much, and, therefore, be no more eflective. 

 Fourth, the advantage which is gained is simply this : That by using 

 little water the animal forms are less widely distributed, and, therefore, 

 the chance of contact with the eggs is increased. Fifth, if the impreg- 

 nation could be made " dry"— that is, without water— it is only reasona- 

 ble to suppose that the egg in the absence of water must imbibe air, and 

 whether this would be conducive to the future well being of the fish re- 

 mains to be seen. It is now generally supposed that the egg absorbs 

 water and not air or oxygen from the water. Sixth, the tendency ffom 

 the commencement has been in our establishment to use less and less 

 water every year for the purpose of impregnation. Starting in the first 

 years of experiment with a pan full, the quantity has been gi-adually 

 decreased, until now barely sufficient is used to cover the eggs. The 

 difference in impregnation in skillful hands between one-quarter inch 

 and one and one-half inches of water may amount to 5 per cent. In 

 unskillful hands it will amount to very much more. Our advice is, to 

 use only enough water to fairly cover the eggs, and until further experi- 

 ments are made not to use less. 



Natural imiwegnation. — Some years since it was thought that a uni- 

 versal panacea for all the ills of trout-breeders had been found in the 

 discovery of a means of natural impregnation. The first invention was 

 made by Mr. Stephen H. Ainsworth, a name well known to and honored by 

 all fish-breeders. His invention was followed by others, using the same 

 jDrinciple, but economizing time and labor to such an extent that if the 

 naturally-impregnated eggs had really been any better than those arti- 

 ficially impregnated, the system would have been perfect. Even now 

 there is great diversity of opinion among trout-breeders, some persons 

 not being willing to use any but naturally -impregnated eggs, and others 

 making no use of them whatever. We ourselves prefer the eggs artifi- 

 cially impregnated, for several reasons. One reason is that many more 

 eggs can be impregnated in this way than by the natural process. If 

 any one will take the trouble to dig up the eggs laid by wild trout in a 

 natural stream he will find that but a very small proportion bear marks 

 of impregnation, the percentage varying from 3 to 10 per cent. The 

 races put down on the Ainsworth plan do much better than this, the 



