1 84 THE COURTSHIP OF ANIMALS 



ment of new birth. The all-important union of these 

 germs is no mere work of chance, as it might seem, but 

 the sperms seek the ova with unerring surety, guided, in 

 this case, by that very efficient substitute for instinct, 

 chemotaxis, or the attraction which certain chemical 

 substances have for lowly organized living bodies. In 

 this case the allurement is furnished by the ova. It is 

 surely no unreasonable surmise that here we have the 

 beginnings of the complex phenomena which the earlier 

 chapters have revealed. On this lower plane we are 

 probably confronted by instinct alone, but from this 

 level upwards intelligence plays an increasingly important 

 part. 



