122 DOMESTICATED TROUT. 



on account of being disturbed, they fall back to the 

 second raceway, where they can generally be kept 

 till the season is over. 



The Spawning Pans. 



The dishes for stripping spawn into are usually 

 rectangular pans, or common milk-pans, with a 

 rectangular depression of a quarter of an inch or so 

 in the bottom. The object of this rectangular feature 

 of the dish is to enable the operator to count the 

 eggs, which of course is easily done for any one layer 

 by counting the number in one row, each way, and 

 multiplying them together. 



It has been demonstrated that fish of the same 

 family can sometimes be crossed. The Chinese have 

 long been in the practice of crossing various breeds 

 of the carp. Trout eggs have been impregnated 

 with salmon milt, and hatched, and salmon eggs im- 

 pregnated with trout milt have hatched.* 



The question whether the progeny will ever repro- 

 duce, has not, I think, been decided by actual exper- 

 iment : but science, popular belief, and analogy all 

 bear uniformly negative testimony. 



* In 1869 I crossed the yellow perch Perca (flavescens) ^Yith 

 the glass-eyed pike (Lucioperca), both percoids, using perch eggs 

 and pike milt. The result was an embryo which continued to 

 develop till the seventh day, when the development suddenly 

 stopped entirely, although the embryo did not die. At this point 

 it resembled the embryo of the same age of the yellow perch 

 proper. 



