42 BIOLOGICAL ASPECTS OF HUMAN PROBLEMS 



ungrateful undertaking to show how essentially sub- 

 servient to these purposes are all the varied struc- 

 tures and devices of the human individual. 



I 



The cells of the body which are devoted to the 

 purposes of reproduction form only a very small 

 portion of the entire body, and this is true of mam- 

 mals generally as well as of the males and females 

 of the human species. Yet these germ cells hold 

 that which forms the basis of new and complete 

 human individuals. The substance of the male 

 germ cell, when brought into contact with the sub- 

 stance of the female germ cell, or ovum, leads to a 

 fusion of materials which not merely secures the 

 groundwork of the embryo, but lays down in that 

 embryo the amazing multiplicity of hereditary 

 materials that carry recognizable family traits, 

 physical, mental, temperamental. The painstaking 

 studies of biologists have shown us that these 

 hereditary qualities are subserved by an elaborate 

 cell mechanism, which has been partially unraveled 

 in some of its complexities, at least in so far as they 

 have to do with structural features. The impreg- 

 nated egg cell in the process of its first division into 

 two new cells typifies the entire development of the 

 completed human being. There within that minute 

 compass lie the materials which predetermine with 

 fatal exactitude the future of the adult form, its 

 sex, its type of stature, the blending of the traits 



