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SEX AND HEREDITY 





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undergone this fatal specialization, which have not lost 



their power of undergoing syngamy, 

 and which therefore have not lost their 

 potential immortality. These cells 

 constitute what is called the gonad- 

 the mass of reproductive cells while 

 the rest of the body is known as the 

 soma. It is only the soma whose days 

 on the earth are numbered any one 

 of the reproductive cells if allowed to 

 undergo syngamy receives in this pro- 

 cess its new lease of life, just as was the 

 case with the Protozoon, and proceeds 

 with the repeated sub-divisions which 

 build up the body of a new individual. 

 The gonad or mass of reproductive 

 cells lives within the soma or main part 

 of the body. It is in it, but yet not 

 of it. It lives its own life, protected, 

 nourished, and carried about by the 

 soma. While the gonad is not mortal 

 in the sense the soma is not necessarily 

 ending its existence in natural death- 



those parts of it which remain within 

 the body are subject to a violent and 

 so to speak accidental death if anything 

 happens to the soma upon which it is 

 dependent for food and so on. 



An important achievement of modern 

 research has been the proof in the 

 case of certain animals that the soma 

 is, as it were, " side-tracked ' from the gonad at an 

 extremely early stage. In some cases indeed when 



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