THE REPRODUCTION OF LIFE. 89 



a portion of its life to the formation of a com- 

 munity cell (germ-cell). The new life thus 

 formed has, therefore, as its constituent elements, 

 a portion of the life that was in each of the five 

 parent units. Now, instead of an organism com- 

 posed of five units of life, or cells, let us suppose 

 that it contains five thousand, or five million; 

 each of these units in this more complex organ- 

 ism has its specific function to perform ; each will 

 give a portion of its life to the formation of a new 

 organism. Out of the principles of life coming 

 from each of these millions of cells, or little lives, 

 a new life is formed, a germ-cell. This germ- 



111 1 1 i t Tile 



cell, though simple in its anatomy, has in it the 

 specific character and form of life of all the mil- 

 lions of cells of the parent organism. It requires 

 only growth and development to make it a dupli- 

 cate of its parent, having the same complex 

 anatomy, functions and sensations that belong to 

 the parent life. 



analyzing these products it has been found that there is - 

 apparently only a single substance in them that fulfills all 

 conditions and can serve as a physical basis of heredity. 

 This is that peculiar substance known to science as chro- 

 matin, which forms an essential part of all animal and plant 

 cells. In all cases of the division of the cells (mitosis) the 

 chromatin is divided between the daughter nucleuli by a 

 peculiar process, which is apparently adapted to secure an 

 equal division, so that each half shall be an exact duplicate 

 of the other. The impregnation of the egg, on the other 

 hand, is the reverse of this. There is a union of the 

 chromatin of the male and female cells to form nuclear Origin of Germ- 

 material for the new germ-cell. When development begins 

 each cell of the body shares equally in the chromatin of the 

 germ-cells of both parents, because all of them are deriva- 

 tions by equal division of the compound or impregnated 



