Crustaceans. 49 



already in the body. His own individuality is 

 apparently of no value ; he finds himself in the 

 grasp of a power far greater than himself. He no 

 longer belongs to himself, but to his race, and un- 

 conscious of what animates him and threatens his 

 very existence, yields himself to the cosmic force 

 which through him reaches out to that greater and 

 more important fact in nature, his race. That he 

 be preserved is not essential; that his race con- 

 tinue is all-important. 



In the female, analogous changes occur, though 

 they are less marked. 



As a rule among all creatures, the tissues of the 

 male are, like the sperm-cell, characterized by more 

 intense activity, by greater tendency to change, 

 than are those of the female. She is structurally 

 more quiescent, he more active. 



When the breeding season approaches the salmon 

 animated by a general impulse, leave the sea in 

 great numbers, and hasten up the rivers. Some- 

 times for hundreds of miles they go, resistlessly 

 impelled by the power within. Overwhelmed by 

 this vital activity they rush along, over rapids, over 

 rocks, — bruised, mangled, never stopping, eating 

 no food, intent only upon the one supreme act of 

 their lives. 



Finally, they select their breeding-place ; the 

 eggs are laid, the fertilizing fluid poured over them ; 

 they are covered with stones and gravel by the 

 parents, and left to their fate. 



4 



