18 



THEOPHILUS S. PAINTER 



synaptic mates of the same size. These two smallest elements 

 are, as will be shown, the sex-chromosomes, the rounded element 

 being the Y-component and the bent rod the X-component. In 



>■ 

 X 



>• 



X 



X 



Text fig. 1 Showing the chromosomes of three spermatogonia, arranged in 

 approximately the order of their size. The X- and Y-chromosomes are labeled. 



figures 1 to 6 the Y-element appears as a rounded body, very 

 conspicuously smaller than the other chromosomes. The X- 

 component frequently shows one end of the rod larger than the 



