1916 Smith; on Salmon Development 107 



active fish from the dark weighed 11.28 per cent more than the active 

 ones from the light. 



3. Chemical analysis showed that, while water made the main dif- 

 ference in weight between the two groups of fish, the percentages of 

 water, protein, fat and ash were nearly the same for the two groups. 



4. After feeding began, numerous determinations of relative weights 

 showed that the fish in the dark continued to increase in weight over those 

 kept in the light. After eight months' feeding the fish from the dark 

 trough weighed 40.73 per cent more than those from the light. 



5. The fish did not develop uniformly in either trough, but those 

 retained in the dark, while averaging much more in weight than those from 

 the light, were also much more uniform in size. 



6. The mortality among those kept in the light was nearly two per 

 cent more than that among those kept in the dark. 



7. Observations upon humpback salmon kept under similar light 

 conditions gave similar results. Those in the light were more active, 

 hatched out more quickly, at least at first, left the bottom of the trough 

 earlier, absorbed the yolk more quickly, and at the time of co:nplete yolk 

 absorption were nearly ten per cent lighter in weight than those from 

 the dark. 



