Value of Sexual Reproduction. 157 



vital impulse which shall cause it to overcome its 

 inertia and take upon itself the prodigious task of 

 producing again that complicated and delicate 

 structure whence it issued. 



Such a task might well appall. And well might 

 the single cell hesitate and wait for inspiration and 

 help to fulfil it. 



This stimulus and inspiration the male-cell is 

 well adapted to bestow. Its excessive activity, 

 united with the excessive nutriment of the female- 

 cell, produces the conditions necessary to enable 

 the now complete cell, the cell which is now in a 

 high degree both male and female in its power, to 

 achieve a growth which shall result in a new being. 



Thus does the separation of the two sexes con- 

 serve the power of the creature. 



Whatever first caused the separation of the 

 sexes, the result was that re-enforced vitality and 

 power of variation upon which the activity of the 

 higher life seems to depend. 



So unless this separation had taken place it is 

 difficult to see by what means the higher life could 

 have arisen. 



The higher life then owes its existence to sexual 

 reproduction. 



Activity is essential to life, and the higher life 

 seems more dependent upon variety to maintain its 

 complex activity than the lower life ; so that where 

 creatures nearl}' related breed together, the lack of 

 diff'erence between them results, in many instances. 



