The Division of Labor. 37 



have to go through the egg transformations, is 

 never seen. The egg, however, in certain low forms, 

 even as high as insects, has the power sometimes 

 to develop without the aid of the sperm-cell, — its 

 store of nutriment and vitality is sufficient to carry 

 it through the difficult transformation, but the tiny, 

 innutrient sperm-cell cannot save itself by unaided 

 development ; it must always unite with the egg-cell 

 if it is to continue its existence. 



In all the higher forms of life, however, neither 

 egg nor sperm cell alone can achieve development; 

 yielding to the vital attraction which draws them 

 together, they unite, and from this inexplicable 

 union comes power to produce a new and perfect 

 creature. 



