146 GRAND STRATEGY OF EVOLUTION 



4. The Functional Attributes of Germ-Cells. Sim- 

 ilar differences in size and in locomotor activities are 

 also the distinguishing attributes of the male and the 

 female germ-cells, or spermatozoon and ovum. The 

 ovum, with its stored-up energy in material form, is 

 larger, in many cases millions of times larger, than 

 its complemental sex cell; but the number is smaller. 

 This costly endowment cannot be economically moved 

 on its own power. Its great weight and volume forbid 

 extensive locomotion; its great organic value forbids 

 its use in hazardous explorations. 



The sperm cells, on the contrary, are never large 

 depots for food. They are always very small, very 

 numerous, and very active; taking advantage in num- 

 bers, and in locomotor powers, to seek out, find, and 

 unite with its complemental germ. 



5. Bisexual Cooperation. Sexual divergence is a 

 good example of what is meant by the term "finding 

 the right constructive ways." It is evident that im- 

 provements in parental benevolence demand the crea- 

 tion of a greater organic surplus, greater storage capa- 

 city for it, and greater power and freedom of move- 

 ment in its instruments of conveyance. But these attri- 

 butes are mutually incompatible; for combined in a 

 single individual each tends to defeat the other. The 

 only way to develop all these attributes is to separate 

 them, develop each one on its own resources, and then 

 recombine them, by means of cooperative action across 

 longer reaches of time and space, into a single func- 

 tion. Nature has discovered this way to increase pa- 

 rental benevolence, and she exploits it to the highest 

 degree in bisexual divergence and bisexual coopera- 



