REPRODUCTION 525 



during childhood, these parts grow but slowly and remain func- 

 tionally incapable during the early years of life; then they com- 

 paratively rapidly increase in size and become physiologically ac- 

 tive; the boy or girl becomes man or woman. 



This period of attaining sexual maturity, known as puberty, 

 takes place from the eleventh to the sixteenth year, and is accom- 

 panied by changes in many parts of the Body. Hair grows more 

 abundantly on the pubes and genital organs, and in the armpits, 

 in the male also on various parts of the face. The lad's shoulders 

 broaden; his larynx enlarges, and lengthening of the vocal cords 

 causes a fall in the pitch of his voice; all the reproductive organs 

 increase in size; fully formed seminal fluid is secreted, and erections 

 of the penis occur. As these changes are completed spontaneous 

 nocturnal seminal emissions take place from time to time during 

 sleep, being usually associated with voluptuous dreams. Many a 

 young man is alarmed by these; he has been kept in ignorance of 

 the whole matter, is too bashful to speak of it, and getting some 

 quack advertisement thrust into his hand in the street is alarmed to 

 learn that his strength is being drained off, and that he is on the 

 highroad to idiocy and impotence unless he place himself in the 

 hands of the advertiser. Lads at this period of life should have 

 been taught that such emissions, when not too frequent and not 

 excited by any voluntary act of their own, are natural and healthy. 

 They may, however, occur too often; if there is any reason to sus- 

 pect this, the family physician should be consulted, as the healthy 

 activity of the sexual organs varies so much in individuals as to 

 make it impossible to lay down numerical rules on the subject. 

 The best preventives in any case are, however, not drugs, but an 

 avoidance of too warm and soft a bed, plenty of muscular exercise, 

 and keeping out of the way of anything likely to excite the sexual 

 instincts. 



In the woman the pelvis enlarges considerably at puberty, and, 

 commonly, more subcutaneous adipose tissue develops over the 

 Body generally, but especially on the breasts and hips; conse- 

 quently the contours become more rounded. The external genera- 

 tive organs increase in size, and the clitoris and nymphae become 

 erectile. The uterus grows considerably, the ovaries enlarge, some 

 Graafian follicles ripen, and menstruation commences. 



Hormones of the Reproductive System. The interrelations of 



