REPRODUCTIVE INSTINCTS 113 



gamete is so sensitive to it that it at once responds, very- 

 much as a young animal swallows when food is in its 

 mouth. There is here something inherited in the nature 

 of the sperm that impels it toward the egg. 



When one gamete comes to be formed by one parent 

 and the other gamete by a wholly different one, it is not 

 enough that the gametes attract one another. They are 

 so separated that neither can influence the other until 

 they are brought together. In order to bring the gametes 

 together, the parents must attract one another. Out of 

 this condition of different parents, carrying different kinds 

 of cells that must be brought together, we have arising 

 the selfish sex desires that lead to the attraction and 

 mating of the parents. These impulses are evidently felt 

 by many of the lower animals as well as by the higher. 

 They are usually stronger in the males than in the females, 

 and cause the males to seek out the females. They are 

 among the most powerful instincts known among animals, 

 and insure that the gametes will be brought together. 



In connection with this purely mating instinct, we find 

 a number of others that are only indirectly connected 

 with mating. Such are the singing and acting instincts of 

 the male birds at the mating season; the actions of spiders 

 at the same period; the fierce fighting instincts of some of 

 the larger male mammals and of some birds; the instinct 

 of flight in the mating of the queen bee. Many other 

 similar phenomena might be mentioned. 



6. Relation of the Sex Instincts to the Reproductive 

 Instincts. It has been repeated frequently that the whole 

 of reproduction is a process of sacrifice. It looks toward 

 the species. The instincts that lead to it may be fairly 

 described as unselfish, without implying that the organism 

 is conscious of it or deserves any credit for it. On the 

 other hand, the instincts of sex point solely to satisfying 

 selfish desires and appetites. They are like hunger and 

 thirst in that they involve satisfaction rather than 

 sacrifice. They are just as selfish as eating. 



