72 GENETICS 



characters shall be produced. A body whose cells contain but 

 one X will produce either male or female secondary sex 

 characters, depending on whether it contains a germ gland 

 having cells of the constitution XO, or cells of the con- 



A 



B 



Figure 23. Diagram of the experiments in exchanging germ glands. 

 A, female body XX (having a pair of X's in each cell), containing 

 a male germ gland XO (having but one X in each cell). B, Male 

 body XO (having but one X in each cell), containing a female germ 

 gland XX (with two X's in each cell). 



stitution XX. And the same is true for the body whose 

 cells bear two X's. 



( 10) By what means do the germ glands affect the devel- 

 opment of the body? 



The germ gland is small and located at a definite place in 

 the body. The secondary sex characters appear in many 

 parts of the body, often situated far from the germ gland. 

 Thus the germ gland influences parts at a distance from it- 

 self. How is this done? 



(11) The suggestion that comes most readily to mind is 

 that each type of germ gland produces a characteristic se- 

 cretion, which passes throughout the body and influences the 

 development of all parts. The secretion from the testis 



