6 CULTURE OF THE MONTANA GRAYLING. 



is then complete within two weeks. If the water is much colder the 

 period will be several days longer. 



The fry is hatched with a very small yolk sac, smaller than the 

 egg, and this sac is absorbed in a week or ten days, the fry then 

 becoming a. free swimming animal about half an inch long, quite 

 slender and delicate, resembling somewhat the fry of whitefish or 

 shad. 



Transportation of eggs. — The usual method of packing and shipping 

 salmon and trout eggs will not answer for grayling eggs. They will 

 not bear crowding or pressm-e, and must be kept at a very low tem- 

 perature. The period of incubation being so brief, there is a possibility 

 of their hatching in transit if they are several days en route and the 

 temperature rises above 42°. This was demonstrated the first sea- 

 son at the Bozeman station, when the eggs were shipped in ordi- 

 nary trout-egg cases, and even with the precaution of packing ice 

 with the moss about the stack of egg trays. Before the next season 

 I devised the refrigerator case, with double wall, by means of wliich 

 the temperature can be kept at 40° or below for any length of 

 time if properly re-iced, and the eggs will reach their destination in 

 excellent condition. 



For the better aeration of the eggs was devised also a special egg 

 tray but one-half inch in depth, with cheese-cloth bottom. No moss 

 is placed over the eggs on the tray, for, as before stated, they will 

 not bear any pressure, and a piece of mosquito netting is all that is 

 required to keep them in position, A space of 2 § to 3 inches is left 

 between the inner wall of the refrigerator case and the stack of egg 

 trays, and this, as well as the hopper on top of the trays, should be 

 kept constantly filled with ice. The hopper has perpendicular sides 

 instead of the flaring sides usual in trout-egg cases, to facilitate 

 re-icing of the space surrounding the stack of trays during transporta- 

 tion. The frames of the egg trays are 1 inch wide, so that when 

 placed in a stack they form a wall 1 inch tliick to separate the eggs 

 from the ice, and there is no possible danger of freezing the eggs; 

 this was demonstrated by experiment. For grayling egg-case labels 

 the precaution "Do not expose to freezing temperature" is always 

 erased, as unnecessary, and moreover, useless when considered in 

 connection with the notice to express messengers to re-ice en route 

 and to keep as cold as possible. 



Feeding the fry. — If stream water containing the minute crusta- 

 ceans that furnish suitable food for the fry, as most streams do, can be 

 supplied to the fry in the hatchery from the first, no artificial feeding 

 will be necessary for a month or six weeks. If, however, only spring 

 water can be had, great care must be exercised and the ingenuity and 

 intelligence of the fish-culturist brought into requisition to discover 

 the best means of feeding. It was found that fresh blood supplied 



