SEX IN LIVING FORMS 117 



reliable test of virginity, however, as commonly re- 

 garded, since it may be destroyed by disease or ac- 

 cident, and may exist even after the occurrence of 

 pregnancy. 



The vagina extends from the vulva to the lower end 

 of the uterus, which it incloses, passing between the 

 bladder and the rectum. The lower extremity of the 

 uterus presents a small opening, which leads into its 

 interior. Upon either side, at its upper and larger end, 

 is a minute opening, the mouth of the Fallopian tube. 

 The latter organs extend from the uterus outward 

 nearly to the ovaries, toward which they present a 

 number of small filaments, one of which is in contact 

 with each ovary. These filaments, together with the 

 interior of the tubes, are covered with a peculiar kind 

 of cells, upon which are minute cilia, or hairs, in con- 

 stant motion. Very curiously, they all move in the 

 same direction, toward the cavity of the uterus. When 

 an ovum escapes from the ovary in connection with 

 menstruation, it is by these delicate hairs propelled 

 along a filament of tissue to the Fallopian tube, and 

 thence by the same means is conveyed to the uterus. 

 It may come in contact with the zoosperms at any point 

 between the ovary and the lower orifice of the uterus, 

 and thus undergo fecundation. 



Puberty.— For a certain period after birth, the 

 sexual organs remain in a partially developed condi- 

 tion. This period varies in duration with different 

 animals, in some cases being very brief, in others, com- 

 prising several years. Upon the attainment of a cer- 

 tain age, the individual becomes sexually perfect, and 

 is then capable of the generative act. This period is 

 called puberty. 



In man, puberty commonly occurs between the ages 



