FISH-CULTURAL PRACTICES IN THE BUREAU OF FISHERIES. 703 



The treatment of eggs of the shad after the milt has been applied is in 

 substance as follows: 



About half a pint of water from the river is dipped into the pan, which is 

 then given a slow rotary motion until the milt is thoroughly mixed with the eggs. 

 This pan with its contents is then set aside and another is used in a repetition 

 of the process. After all the stripping has been done the milt is washed from each 

 pan of eggs by dipping water from the river and pouring it off, repeating until 

 the milky color of the water disappears. The pans of eggs, with about i pint 

 of water in each, are then set aside, and after fifteen or twenty minutes it will be 

 noticed that the eggs are absorbing the water. A little more water must then 

 be added from time to time until they have fully expanded, which usually 

 requires from forty to sixty minutes, but varies somewhat with the water tem- 

 perature. When fully water-hardened, the eggs feel like shot to the touch of 

 the fingers, and now, less sensitive to concussion, are ready to be transferred 

 to the buckets in which it is customary to convey them to the hatchery. 



En route to the hatchery it may be necessary every twenty or thirty min- 

 utes to replace the water on the eggs with water from the river in order to 

 maintain an even temperature, the air on very cool nights affecting the water 

 in the buckets to such degree as to injure the eggs. 



The first thirty-six to forty-eight hours after arrival at the hatchery is the 

 period of greatest mortality to the eggs, and until this has passed they are kept 

 in open-top jars or in McDonald jars without tops, the water flowing through 

 them being allowed to waste over the tops of the jars. The dead eggs being 

 lighter than the live ones work toward the surface and are easily removed with 

 a siphon of J<-inch rubber tubing. The good eggs are then measured (by means 

 of a device which will be described later) and their number is accredited to the 

 fisherman from whom they were obtained. They are then put up for hatching in 

 the McDonald Universal (i. e., closed-top) hatching jars, which are arranged on 

 specially constructed tables in connection with rectangular glass aquaria or 

 receiving tanks and subjected to a current of about 4 or 5 pints of water per 

 minute at 8 pounds pressure, which is sufficient slightly to elevate the eggs 

 from the bottom of the jar, thus giving the entire mass a slow revolving or boil- 

 ing motion. The number of eggs to each jar is from 85,000 to 100,000. As the 

 young fish emerge from the eggs they rise toward the surface, where they come 

 in contact with the suction outlet tube of the jar and pass through it with the 

 waste water to the collecting tanks. From this they may be removed to the 

 distributing cans by means of a ><-inch rubber siphon. Another method of 

 removing them is to dip them from the aquaria after siphoning off a portion of 

 the water. By this method, emptying an equal number of dippers of fry into 

 each can, it is possible to quite equally distribute the total number to be 

 removed. 



