TROUT-BREEDING IN WINTER 19I 



will not have received them till this period, and so 

 he has missed a very interesting part of the fish's 

 history. To supply, in some part, this omission, I 

 will give just those little details which can be seen 

 by the aid of a good lens, which, by the by, should 

 find a place in every naturalist's outfit. 



"For some time," says Mr. Francis Francis in 

 his "Fish Culture" (after impregnation), "little 

 change is observable in the ova ; but at length 

 little globules of an oily looking substance are 

 formed. By degrees these densify, and by the aid 

 of a strong glass a thin, whitish line may be traced 

 coiled within the egg. This is the earliest devel- 

 opment of the spinal column, and, of course, it 

 becomes more distinct as the animal becomes 

 more formed. And about the fifth or sixth week 

 (in water of moderate temperature we may say 

 usually from the thirty-fifth to the forty-fifth day) 

 a small dark speck, probably, on examination, two 

 black specks, will be observable. These are the 

 eyes of embryos, the form of which may now be 

 traced almost by the naked eye. In a few days 

 the eyes become distinct, and the embryo may 

 now be discerned without the aid of a glass, mov- 

 ing and turning round the egg." 



