432 EEPOET OF COMMISSIONER OF FISH AND FISHERIES. 



a fine lot of spawn in the pans and not a single ripe male to be found 

 to fertilize it with, and it has, to the great disappointment of the 

 breeder, to be thrown away as worthless. Tliis scarcity of ripe males, 

 late in the season, may possibly be attributed to this fact, that many of 

 them ripen so much earlier in the season than the females. 



The amount of milt that can be expressed at one time is limited to a 

 small quantity, but a very small quantity will impregnate a very large 

 number of eggs, and it is asserted by some to be the more successful way, 

 though usually the milt of a large number is made use of when available. 

 Under the microscope the milt is seen to be thronged with myriads of 

 spermatozoa. In impregnating by the dry method their sttong impulse for 

 movement is observed, by placing a small quantity of the milt on one side 

 of a quantity of eggs covering the bottom of a pan, when, if left to itself 

 but a short time, it will be found to have diffused itself between and 

 among all the eggs. If but one of the spermatozoa is needed to fertilize 

 each egg, but a very small quantity of the milt is required. 



9. — THE IMPREGNATION OF SHAD EGGS. 



The ova from the female being collected in the pan with a small 

 quantity of water, a slight pressure on the ripe male near the anal open- 

 ing will force out two or three jets'of the milt, which, falling into the 

 l^an, is stirred by a gentle movement of the hand with the fingers 

 spread, care being taken to keep the fingers from contact with the sides 

 or bottom of the pan, as in that case some of the eggs would be crushed 

 The milt being diifused throughout the water, the pan is left for a few 

 moments to allow the spermatozoa to come in contact with the eggs- 

 The pan should then be filled full of fresh water, and gently swaj^ed 

 until the water charged with milt is thoroughly mixed with the fresh 

 water and the eggs slightly rinsed, when soon afterward the water may 

 be j)oured nearly off and the pan refilled with fresh water, and after a 

 slight and always gentle rinsing up of the eggs, the pan may be al- 

 lowed to stand for several minutes. 



The fact has been referred to that the eggs were not discernible to 

 the touch when put into the j^an, nor is there any change in this par- 

 ticular, if no milt is added ; at any rate, for the length of time that the 

 eggs have been observed in this condition, a half hour or more. For 

 about twelve or thirteen minutes, when the temperature of the water was 

 about 70°, after the milt was added, no change was observed, but about 

 this time a careful movement of the fingers in the pan discerned their 

 presence, and in a little more than twenty minutes from the time the 

 milt was applied they were felt like shot against the fingers, and to an 

 experienced eye were observed to have increased slightly in size.* This 



* Dr. E. M. Scbaelier, of the United States Army Medical Museum, while making in- 

 vestigations with tlie microscope at the station, found that the increase in size waa 

 nearly nine-tvveutieths of their original diameter in one hour and tifteen minutes after 

 contact with the milt. 



