100 Thirty-ninth Annual Mcctiny 



hardening there is an increase in the size of certain species of 

 fish eggs so considerable as to call for recognition in practical 

 fish culture. An output of nominally 100,000,000 eyed 

 whitefish eggs, for instance, measured when eyed and com- 

 puted by the usual standard for green eggs would add 

 10,000,000 to 15,000,000 to the actual number planted. 

 Reports may thus unwittingly or'unintentionally be increased 

 by many millions. 



In addition to their practical significance, these percentages 

 suggest the possibility of other interesting developments. 

 The rainbow trout tgg, it seems, has peculiarities which, so 

 far as the present data are concerned, removes it from the 

 considerations applicable to the other species tested. Its 

 near relative, the landlocked salmon, shows little increase in 

 size, if an}', after water hardening, and further tests may be 

 expected to show closer similarity of characteristics between 

 these two. It would be of interest to know what characters 

 in the eggs control or accompany the varying degrees of 

 expansion. Have the semi-buoyant eggs, which are kept 

 constantly in motion, greater absorptive power than the 

 heavy eggs, wdiich remain practically unmo\'ed during incu- 

 bation? Is the increase due to absorption of water, or is it 

 perhaps, a physiological growth? Answer to these questions 

 is possibly to be found in biological literature, but in the 

 various authorities I have consulted there is a striking ab- 

 sence of any mention of increase in size of fish eggs after the 

 early segmentation stages. The question is one well worth 

 further investigation. 



