60 Heredity and Social Progress 



that disturb the rhythm of the body than 

 are those areas with more nerves. They are 

 therefore cut off or reduced in size by the 

 nervous shocks. The form of the organism is 

 more and more determined by the position 

 of its nerves, for every development in the 

 nerves modifies some parts of the organism 

 by its processes, and injures other parts by 

 the shocks which the older parts are least 

 able to withstand. The development of 

 nerves thus induces both positive and nega- 

 tive changes and renders organisms progres- 

 sive as long as new nutrition gives the growth 

 that produces, first, folds, and secondly, the 

 necessary new nerves. 



SUMMARY 



i. Reduction is a phenomenon of sexual reproduction. 

 Two polar bodies are in succession separated from the 

 female germ cell to make it ready for the reception of the 

 male germ. Reduction is a movement towards simplicity 

 which goes so far that some elements are cast out that 

 must be replaced before growth is renewed. This simplifi- 

 cation may be peculiar to sexual reproduction, but there 

 are indications that it is an example of the way in which 

 all tissue is brought back to simple conditions. 



