228 PHYSICAL BASIS OF CIVILIZATION 



The above, however, does not justify the inference 

 that the bodies of the parents, which are composed 

 of somatic cells, stand in causal relations toward 

 the nature and growth of the new organisms. The 

 reproductive cells, which before they were conjugated 

 were situated within these bodies of the parents, 

 are the real causes. Since these cells must in nature 

 and composition be almost exactly like those which 

 built up the bodies of the parents, therefore are 

 these bodies true indications of the kind of bodies 

 which the reproductive cells within them are competent 

 to build up. It is in this sense that the bodies of 

 the parents have been mentioned in the last para- 

 graph. Why can it be asserted that the reproduc- 

 tive cells within the bodies of the parents are exactly 

 like the reproductive cells which built up these 

 bodies ? Because the primary material for the cells 

 within was derived by one of the earliest segmenta- 

 tions from the fertilized ovum which built up the 

 body of the parent and the secondary material for 

 these cells within was obtained by assimilation; 

 and by the process of assimilation the material 

 added obviously must be qualitatively equal to 

 the material it is added to. 



When by the process above explained the adult 

 form has been attained, then thereafter the material 

 added by cell division is mainly instrumental in 

 replacing portions of structures that have been 

 broken down by functional activity. This part of 

 the process continues with varying energy during 



