ARTIFICIAL PROPAGATION OF TROUT. 23 



ing conditions of the water supply. However, they should be care- 

 fully gone over at least once a week. One attendant at a field station 

 can care for a million eggs unless the percentage of fertilization is 

 excessively low. 



Trout eggs are extremely sensitive to shock during the period ex- 

 tending from two to four days after they have been laid down in the 

 hatchery up to the time when the eyes of the developing embryo are 

 discernible to the unaided eye, and any movement of the trays of eggs 

 at this stage is liable to result in heavy loss. The exact length of this 

 period is dependent on the water temperature. It is known to fish- 

 culturists as the " tender stage," and until it is past it is advisable 

 to leave the eggs undisturbed so far as possible. If it becomes nec- 

 essary to remove dead eggs to prevent the spread of fungus, as in- 

 dicated above, it should be done with the utmost care. 



PACKING THE EGGS FOR SHIPMENT. 



At the proper stage of development the eggs may be transported 

 for long distances without material loss if skillfully packed. Cases 

 of a great variety of shapes and sizes with an equal variation in 

 the styles of trays and the methods of insulation have been used. 

 The essential requirements for the successful transportation of trout 

 eggs are, (1) a package so insulated that it will preserve a uniformly 

 low temperature on the eggs; (2) protection from undue jars or 

 shocks; (3) the maintenance to the end of the journey of a rea- 

 sonable amount of moisture. Any package that will accomplish allol 

 these things may be considered fairly satisfactory, although as such 

 shipments are usually sent by express the weight of the package 

 also becomes an important item. In this way the so-called bulk 

 method of packing trout eggs is more economical than the use of 

 trays, and for shipments involving not more than 48 hours' time it 

 may be satisfactorily applied in most cases to the transfer of eyed 

 eggs from the collecting fields to the main hatcheries. For journeys 

 of longer duration the mode of packing described on page 25 is 

 preferable. 



As regards the bulk method, the size of the case will depend upon 

 the number of eggs to be shipped. The case consists of one or more 

 inner boxes for eggs and an outer box of sufficient size to hold them 

 and allow 4 inches of space all around for packing. The inner 

 boxes are made of one-half-inch lumber with the bottoms left partially 

 open to permit the surplus water to drain off and to allow for swelling 

 of the lumber when wet. An egg box 12 by 15 inches and 4 inches 

 deep will carry from 80,000 to 100,000 eggs, the actual number 

 depending on their size. Three of these boxes packed in a single 

 case, containing approximately 300,000 eggs, will weigh about 125 

 pounds. 



AVhile a great variety of materials, including leaves, straw, saw- 

 dust, shavings, etc., have been used as an insulating medium in pack- 

 ing fish eggs for shipment, probably nothing superior to sphagnum 

 moss for the purpose has been found. "When saturated with water, 

 it retains the moisture for a long time and is thus valuable for use 

 on the egg trays or boxes. When dry, it packs closely around the 

 egg trays and is a most excellent nonconductor of heat or cold. Fur- 

 ther, it has not the tendency to " heat " that certain other materials 

 possess. 



