CHAPTER TWENTY-ONE. 

 REPRODUCTIVE INSTINCTS. 



1. Introduction. Thus far we have been discussing 

 reproduction chiefly as a process whereby individuals 

 increase the number of species. Reproduction thus viewed 

 seems to be a result that can be had by a number of 

 different kinds of machinery, much as we may cultivate 

 corn with a crooked stick, or with a hoe, a single plow, or 

 an up-to-date cultivator. The methods differ in efficiency, 

 but all lead to the same result. The real meaning of the 

 process is very much the same whatever method is used. 



2. Tendencies in Life. It does not explain the fact of 

 reproduction, however, merely to say that the species 

 would die out if the individuals do not reproduce. What 

 difference does it make to the individual if the species 

 does die out? We cannot imagine that the individual 

 plant or animal is conscious of this fact, or that 

 it is directly influenced in its behavior by this fact. Deep 

 within the living thing is the tendency to grow, and equally 

 the tendency to divide. We have no real explanation of 

 how it comes to be, but we do know that as we ascend the 

 scale of life the process of reproduction becomes more and 

 more complex. There come also to be various tendencies 

 in plants and animals, associated with reproduction, that 

 we describe as habits or instincts. Some of these are 

 peculiarly important and interesting, and help make 

 reproduction more efficient. 



3. The Meaning of Instincts. If an individual learns to 



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