THE HISTORY OF FISH-CULTURE. 541 



water enongli to cover the eggs ex])ected to be obtained, and a little ex- 

 perience will enable the operator to estimate the quantity accurately 

 enough. An excess of water is injurious because it dilutes the milt, dis- 

 perses the seminal animalcules, and diminishes the chances of impregna- 

 tion." On another page he says : " Since, then, the egg completes its ab- 

 sorption rapidly, and the currents attracted by it very soon cease, and 

 since the seminal animalcules speedily lose their vitality in water, it is a 

 matterof great practical importance to perform the processes for facilitat- 

 ing impregnation with as little loss of time as possible. The best method 

 is doubtless to mix the milt with water and then immediately drop the 

 spawn into the mixture, as the attraction arising from the absorption 

 of water by the egg serves to direct and facilicate the movement of the 

 animalcule toward the orifice, and this conclusion is abundantly estab- 

 lished by observation." 



It has been stated that Seth Green early applied these principles in 

 fecundating eggs, and it is regarded as largely the secret of his success. 

 If so, however, he kept his method a profound secret, not exercising it 

 in i)ubiic, ov making any reference to it in his work. 



In 1872 Mr. Wilmo.t, in his report* to the Department, asserts that ex- 

 perience taught him each year to use less and less water, and, finally by 

 experiment, that his greatest results were attained without water, and 

 in 1872 he adopted the system of dry impregnation. 



The American system of dry impregnation, which from present record 

 would seem to have been originated by Mr. Atkins t in 1871, diiiered 

 from that of Vogt and of Vrasski, inasmuch as he did not dilute the 

 milt or allow water to come in contact with eggs or milt until a full ap- 

 plication of pure milt had been made. The contact was secured by 

 moving the eggs rapidly in a pan, the milt and eggs being thus thor- 

 oughly mixed, after which water was poured into the mixture. 



In the fall of 1872 Mr. H. F. Dousman, of Waterville, Wis., extensively 

 engaged in trout-culture, applied the dry method of fecundation and 

 frequently with this modification, that, instead of obtaining contact of 

 eggs and milt by stirring them together, he trusted entirely to the per- 

 sistant impulses of the spermatozoa to move directlj^ forward, and cov- 

 ering the bottom of a pan with ripe trout-eggs, applied the milt in 

 several spots, when, after a few minutes, it could be detected by its milky 

 appearance to have diffused itself among all the eggs. 



Mr. Livingston Stone, in his operations in California in 1872, while 

 l^rocuriug spawn of the Sacramento salmon, {Salmo qninnat,) continued 

 putting eggs into the impregnating pans until they were half filled be- 

 fore he applied the milt, and then stirred them with his hand until thor- 

 oughly mixed before he x)oured in water. He succeeded by this method 

 in impregnating nearly 100 per centum of the eggs.| 



* Annual Report of the Department of Marine and Fisheries (Canada) for the year 

 ending '.iOth June, 1872. Appendices of the Fisheries Branch of Department Marine 

 and Fisheries, p. 96. 



t See page 239. t See page 173. 



