204 



THE THEORY OF THE GENE 



the latter, show that man belongs to the XX-XO or to the 

 XX-XY type. The number of chromosomes in the human 

 race has only recently been determined with any degree 

 of accuracy. The earlier observations giving fewer have 



Fig. 117. 



Maturation division of the germ-cells of man, illustrating the 

 separation of the X- and the Y-ehromosome. (After Painter.) 



been shown to be faulty, owing to the tendency of the 

 chromosomes to stick together in groups when the cells 

 are preserved. De Winiwarter gives the number as 48 

 in the female (n=24) and 47 in the male (Fig. 116a), 

 and this count is practically confirmed by Painter, who 

 recently has shown that there is also present in the 

 male a small chromosome that acts as the mate of a much 



