THE CELL AND PROTOPLASM. 



123 



ing is a general description of the process derived 

 from the study of a large variety of animals and 

 plants. 



In the cells of the body of the animal to 

 which this description applies there are four 

 chromosomes. This is true of all the cells of 

 the animal except the sexual cells. The eggs 

 arise from the other cells of the body, but 

 during their growth the chromatin splits in such 

 a way that the egg contains double the number 



FIG. 34. FIG. 35. 



FIG. 34. This and the following figures represent the process of 

 fertilization of an egg. In all figures cr is the chromosomes; 

 cs represents the cell substance (omitted in the following 

 figures) ; me is the male reproductive cell lying in contact 

 with the egg ; mn is the male nucleus after entering the egg. 



FIG. 35. The egg centrosome has divided, and the male cell with its 

 centrosome has entered the egg. 



of chromosomes, i.e. eight (Fig. 34). If this egg 

 should now unite with the other reproductive 

 cell from the male, the resulting fertilized egg 

 would plainly contain a number of chromosomes 

 larger than that normal for this species of animal. 

 As a result the next generation would have a 

 larger number of chromosomes in each cell than 



