BULLETIN OF THE UNITED STATES FISH COMMISSION. 363 



is very well accomplished with this inexpensive apparatus; it requires, 

 however, a greater head of water than the jar incubators, and for this 

 reason the success of the experiment as tried was somewhat impaired. 



PACKING FISH EGGS FOR SHIPMENT. 



There are a number of methods employed in preparing the eggs for 

 shipping. The conditions most favorable to successful transportation 

 are those which will best maintain a moderate degree of moisture of 

 the eggs, and the lowest possible temperature that will not impair their 

 vitality. Experiments have shown that 32° F. is the temperature best 

 calculated to preserve the statu quo of the various species treated at 

 this hatchery. Under the conditions named, development of the em- 

 bryo proceeds very slowly, almost imperceptibly ; the development of 

 conferva? is likewise retarded. An ample period of time is therefore 

 given them to make long journeys without losses, if the proper condi- 

 tions are maintained. Various experiments have been made from time 

 to time, by diversifying the details of preparation, but the method 

 which has met with the greatest measure of success is substantially as 

 follows : A sufficient number of canton-flannel trays are made to hold 

 the eggs, and a case is constructed of such a size as to contain the 

 trays when superimposed upon each other, and to allow 4 to 6 inches of 

 space around the sides for packiug material. The trays are placed in 

 a tank of ice-water not less than an hour before eggs are transferred 

 thereto. A quantity of eggs are transferred from the hatching vessels 

 to wire-trays in the picking-trough, and feathered over to throw up 

 dead or unimpregnated eggs, which are removed with nippers. The 

 sound eggs are then collected by overturning and submerging the trays 

 into a large tin vessel partly filled with water; thence they are skimmed 

 up and measured in a graduate * and poured into the shipping trays, 

 which are immediately taken to the packing room, where the tempera- 

 ture is between 30° and 40° F. The trays are then thoroughly drained 

 of superfluous water, and the eggs are spread uniformly two layers in 

 depth, with a half-inch margin of flannel between the eggs and wood 

 frame of the tray. A single fold of dampened millinet is then thrown 

 over the eggs, and over this a sufficient quantity of live moss, washed 

 and wrung out to prevent drainage, to fill the tray when rather snugly 

 pressed down. When admissible, the trays are allowed to stand in 

 temperature a little below the freezing point until needles of ice have 

 begun to form in the moss ; they are then placed one above another and 

 held to position by cleats nailed to top and bottom boards. The pack- 



* The following is the standard of measurement used at the Northville N hatchery : 

 Whitefish, 1,250 ; hrook trout, 450 ; lake trout, 200 to the fluid ounce. Egg-s of white- 

 fish and lake trout vary hut little in size. Brook-trout eggs, however, depend in size 

 a good deal on the age of the parent fish. Thus the product of the first egg-bearing 

 period (fish twenty months old) will run about 500 to the ounce ; from trout three and 

 four years old, about 400 to 425 to the ounce, making 450 a fair average. 



