PART IX 

 REPRODUCTION 



SECTION XXX 

 THE REPRODUCTIVE ORGANS 



CHAPTER XCIII 

 GROWTH, REGENERATION AND REPRODUCTION 



Direct Cell-division or Amitosis. — The preceding pages have been 

 devoted very largely to a discussion of the processes of life as we find 

 them in the adult animal. Looked at in a very general way, these 

 processes present themselves as phenomena of activity and growth. 

 Both of these take place at the expense of the inorganic and organic 

 material of the surrounding medium, and are the direct outcome of 

 stimulations. Consequently, life is not . spontaneous, but consists 

 merely of responses to external and internal impressions. Sooner or 

 later, however, these reactions cease and retrogression gains the upper 

 hand. Henceforth dissimilation continues uninterruptedly until the 

 complex animal machine has ceased to exist as a living entity. Thus, 

 death is merely a phenomenon of nature, brought about by a serious 

 derangement of the processes upon which life is based. It is the 

 climax of all physiological activities. 



Since the chief consequence of death is the extinction of the indi- 

 vidual, not only the existence of a certain species but also that of all 

 animal Ufe would be endangered. In order to prevent such an out- 

 come, nature has provided a process of rejuvenation by means of which 

 new living entities may be brought into existence to take the places of 

 those used up. This constitutes the process of reproduction. Funda- 

 mentally considered, the aspect of reproduction is the same as that of 

 growth, because it strives to accomplish a multiplication of the living 

 substance at the expense of the surrounding material. In the case of 

 growth, however, the new substance is affixed to the same entity, while 

 in the case of reproduction, it is moulded into an entity sparate from 

 the original. 



Attention has previously been called to the fact that the size of 

 any given unit of Hving matter is limited, because it is held together 



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