178 VARIABLE TIME OF HATCHING. 



hatched at different times, even though kept 

 in the same vessel and treated exactly alike; 

 and the young fish likewise to differ in size, in 

 activity and in strength. In the instance of 

 the ova of salmon, I have witnessed in the 

 time of hatching, under the same circumstances, 

 a difference of seventeen days ; and in that 

 of the charr a difference of ten days and more, 

 with a slight variation of circumstances, such 

 as a difference of two or three degrees of tem- 

 perature. Further, as regards the absorption 

 or consumption of the yolk, by which, for a 

 certain time the young fish are supported, that 

 too in different individuals is variable in point 

 of time. Such variations at first, may seem 

 somewhat startling, but when we consider the 

 course of nature generally, it seems rather in ac- 

 cordance with that course; her laws, especially 

 in regard to living beings, having a certain lati- 

 tude, exceeding commonly our idea of them. 

 It is well to keep this in mind ; it may help 

 to explain and reconcile disputed points and 

 differences of opinion, as, for instance, regarding 

 the time that elapses between the hatching of 

 the ova of the salmon and the migration of the 

 salmon fry to the sea. 



