Figure 17. Diagram to illustrate the relation of body cells and 

 germ cells, and the origin of both from the fertilized egg. Only a 

 single pair of chromosomes is represented in each cell. At A are the 

 two gametes (sperm and ovum) which unite to produce the fertilized 

 egg B ; each gamete contains one chromosome of the pair. The fer- 

 tilized egg B divides, producing body cells C, among which is the 

 primordial germ cell P. The primordial germ cell divides to produce 

 many immature germ cells (E). The immature germ cell enlarges, 

 the two chromosomes of a pair conjugating (F), then divides into 

 four germ cells (G, H), each containing but one chromosome of the 

 pair. (In the female three of the four germ cells (H) thus formed 

 are not functional.) 



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