122 SEX 



of bodily ripening, which is quickened by 

 the maturation of sex. In illustration of the 

 ordinary changes which mark this stage in 

 the life of the body, we notice the beginning of 

 the coalescence of the caps of the long bones 

 with their shafts, and, as a negative character, 

 the disappearance of the thymus gland, which 

 is a distinctively juvenile organ. As sexual 

 changes, the male shows an increased growth 

 of hair, an enlargement of the larynx, and 

 an increase in the size of the genital organs ; 

 the female shows a change in the shape and 

 size of the uterus, an enlargement of the 

 mammary glands, and the onset of menstrua- 

 tion. While the reproductive organs, through 

 their internal secretions, have been influential 

 all through development, they come to have 

 a special influence when mature. And besides 

 the influence of the internal secretions, there 

 is that due to the fact that the essential or 

 germinal parts of the gonads have passed 

 into more active functioning. 



At the time of sexual maturity, according 

 to Steinach, the brain is greatly influenced 

 by the internal secretions, it is " eroticised," 

 and this has far-reaching influences on the 

 metabolism. Through the vaso-motor system 

 the changes in the brain affect the blood- 

 supply to various parts of the body. The 

 organism becomes impressionable to the other 

 sex in a new way. Certain sympathetic 

 ganglia become increasingly susceptible to 

 peripheral stimulation. And the brain-ganglia 

 become disposed to lower the tonus of certain 

 inhibitory centres in the spinal cord. Of 

 course, there are also psychical factors which, 



