After this period of rest, the now fertilized eggs are dumped into the brood 

 receptacle. During the first few hours after fertilization the eggs are very resistant 

 and ?/ill even stand transportation. ',Yith eggs of maranes and pike such a transportation 

 is almost always necessary. (For shipments it is best to use white metal cans, not 

 "galvanized" sheet iron or otherwise zinc-coated metal cans.) These cans are filled to 

 1/4. with eggs and then completely filled up with water. Before this is done, the egjjs 

 have to be thoroughly washed, in order to free them from all dirt, slime and now super- 

 fluous spermatozoids. For at least 15 minutes, the eggs are rinsed and stirred with ever 

 renewed, clean v/ater. Stirring up will bring eventual scales, even feces to the surface. 

 These are removed vdth the forceps. During shipment (which I have successfully done for 

 a period of 12 hours), the v/ater is not to be renewed. As mentioned before, it is also 

 possible to ship eggs and milt in dry state, best in thermos bottles, but this is seldom 

 done in practice. 



4.. The Construction and Arrangement of Brood Apparatus 

 for the Artificial Hatching of Fish Eggs , 



The importance of proper incubation of trout eggs cannot be overestimated from the 

 economical viewpoint (Fig. 30). And since trout eggs are relatively large, about the 

 size of a pea, the process of their incubation is quite easy. Among the many specially 

 constructed apparatuses or those with unimportant modifications, only the California 

 incubating apparatus (under current apparatus) and the long current apparatus have 

 maintained a considerable use in practice. I v;ill describe here the mode of their con- 

 struction, and which from my experiences appears to be the most practical one. 



•«». *^ 



Fig. 25, Undercurrent Apparatus (California Incubator) 

 for the incubation of trout eggs. The inner sieve box, 

 for the sake of clearness, has also been drawn into the 

 covered portion. The sieve box is covered with a lid 

 during the incubation (30 cm. x ^0 cm. ), 



The construction of the California brood basket — an "undercurrent" device — is seen 

 in Fig. 25. The eggs rest upon a sieve-like frame and the vjater vrashes them from below. 

 The result is that oxygen and fresh water supply are especially good, and any mud present 

 in the v.'ater will settle at the bottom of the baskets. The baskets should not be much 

 longer than about 30 to ^0 centimeters, in order to have cin "even undercurrent". The 

 wider the apparatus, the more attention must be paid to an even v/ater current all through 

 the baskets. In the sketch (Fig. 25), it was attempted to achieve this by an outflow 

 from the i>^ole width of the basket instead of through a pipe in the niiddle of it. An 



109 



