BIOLOGICAL DEATH AND REPRODUCTION 



types of cells in the organism can probably be greater 

 than the average life expectancy of the entire organ- 

 ism, which is likely to be more closely determined by 

 its least resistant, rather than by its most resistant cells. 



Death then, appears to be a result of the effects 

 predictable on the basis of the Second Law of Thermo- 

 dynamics upon the materials comprising living organ- 

 isms. Cell fusion, or conjugation, therefore, seems to be 

 the method by means of which a species of relatively 

 greater complexity succeeds in preserving itself. For 

 the individual of any such species, however, death is a 

 thermodynamic necessity. 



The mechanism of conjugation by means of which 

 the somatic mutation damage is prevented from en- 

 feebling the new generation is ingenious and amazingly 

 effective. It is indeed difficult to contemplate another 

 type of process which could in so successful a manner 

 solve the problem of permitting living matter to escape 

 thermodynamic annihilation. 



For completeness, another method of rejuvenation 

 which is found in certain protozoa should be men- 

 tioned here. This process is known as endomixis. In 

 endomixis rearrangements or exchanges between the 

 nuclei of the same cell take place. This internal process 

 apparently re-establishes the cell-orderliness needed 

 for proper function which has been adversely affected 

 by somatic mutations. It may be regarded as a sort of 

 internal conjugation. Certainly, the existence of this 



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