540 EEPOET OF COMMISSIONER OF FISH AND FISHERIES. 



tbe attempt at obtaining eggs from salmon within the bonndaries of the 

 United States was begun* by Mr. Atkins, of Bucksport, Me. 



The method adopted by him for procuring seed-fishes is by far the 

 most efficient and certain of large results of any in use. The salmon, 

 during the whole season prior to spawning, are obtained from the nets 

 of the fishermen by purchase, and are moved by means of wells or 

 live-boxes to the ponds prepared for their reception, where they are 

 retained until the ova are ripe. By taking advantage of their instinct 

 for seeking suitable spawning j)laces they are at this time enticed 

 into raceways, where they are easily taken by the operators, and 

 the spawn and milt expressed, when they are returned alive to the 

 ponds. Several experiments were made to discover what character 

 of water was required to preserve salmon in good, healthy condition 

 while confined in the ponds. The conditions of temperature below a 

 maximum of 73°, or the depth above a minimum of four feet, did not 

 seem to affect them as much as the penetration of light into the body 

 of water, as the experiments made in water darkened from the coloring 

 ])roperties of vegetation through which it ran were more successful than 

 in very clear water, even where the depth was slightly increased and the 

 temperature much lower. 



During his first year's experiments Mr. Atkins employed the dry 

 method of fecundation, which had been brought to the notice of Ameri- 

 can fish-culturists by the translation from the Bulletin de la Societe 

 d^Acclimatafion, August, 1871, of the observations of Vladimir Pavlo- 

 vitche Yrasski in 1856, By reference to the essay on fish culture, by Carl 

 Vogt, the embryologist, of Geneva, Switzerland, of which an abridged 

 translation was published by George P. Marsh in 1857,t it will be seen 

 that Vrasski was anticipated by him in the announcement at least, if not 

 the discovery of this method.^ 



In describing the process of artificial impregnation, Vogt says: "The 

 eggs and milt should be received in a shallow vessel containing barely 



* See page 233. 



t Report on the Artificial Propagation of Fish, by George P. Marsh, Burlington, Vt., 

 1857. 



t The studies of the embryologists from the time of You Baer discovered the fact 

 that the spermatozoa of many animals retained the power of movement for a longtime 

 while subjected to a microscopic examination. In fact, Von Baer believed them to have 

 a separate, independent life from the animal to which they belonged. This view was 

 confirmed by others, and it was carried so far as to regard them as possibly infusoria, 

 and as in their habit entozoicor ijai'asitic, within the organs of animals. The fact of 

 their independent life was first disputed by Treviranus, who believed their movement 

 to possess no voluntary character, and that in their structure and properties they were 

 analogous to fibrils and particles in the pollen of plants. The later physiologists are 

 inclined to accept the latter view, so that their possession of life is as a part of the 

 animal from which thej' are thrown oft". They have a capacity for sustaining vitality 

 for a time after separation, somewhat as the blood-corpuscles do in the operation of 

 transfusion, or as in epithelial cells. Tliey thus become the medium for the transmis- 

 sion of a portion of the life of the male to the egg of the female, which previously is 

 inert. 



