38 BASIS OF THE PROBLEM 



primarily with the object of throwing Hght upon the position of 

 species in a state of nature, but in order to prepare the way for 

 a discussion of the shape which the problem has assumed in the 

 case of man. 



2. At the basis of both aspects of the problem lies the fact of 

 reproduction. All organisms reproduce their kind. Reproduction 

 is clearly a necessity, because all living things are liable to meet 

 death by accident and, unless there was reproduction, every 

 species would soon be extinguished. It is worth while observing 

 that among all higher forms of life a more or less clearly defined 

 hmit to the duration of life has been evolved. In other words, 

 natural death after a certain period ensues. It would seem that 

 natural death has been evolved in the following manner. All 

 organisms are subject to the wear and tear of daily life, to meet 

 which there is a faculty of recuperation. Among the lower 

 forms this faculty is very pronounced. The whole animal can 

 be regenerated from a small fragment and, as a result, very 

 serious accidents are not fatal. Among the higher forms there 

 goes, generally speaking, with the advance in structure a loss of 

 the power of regeneration, until among the highest there is 

 little or no power of regeneration ; for a certain average length 

 of time the highest organisms withstand the batterings of daily 

 life, gradually fail to recuperate, and finally die. Given the 

 necessity of reproduction to provide for the continuance of the 

 species against accident to its members, this further evolution 

 is not difficult to understand. A power of recovery from all but 

 the most extreme forms of accident is present among the simpler 

 types ; the retention of such a power of recovery tends to be 

 incompatible with increasing complexity of structure, and it 

 has, so to speak, been more economical to evolve organisms 

 provided with a power of recuperation only against normal wear 

 and tear over the period during which they remain capable of 

 reproduction. The higher types therefore, after reproducing 

 their kind, die and thus the battle of hfe is always being resumed 

 by fresh generations. 



3. That in some such fashion reproduction has to be explained 

 seems clear ; but we are concerned here with the facts of reproduc- 

 tion. It will be necessary later to go into the nature of reproduc- 

 tion in greater detail ; all that needs to be said here can be stated 

 quite shortly. There are two forms of reproduction, known respec- 



