THE WAY LIFE BEGINS 



65 



reduction of nuclear material is made so that when the union 

 with the sperm cell (which has also been reduced) occurs there 

 will be no absolute increase in this substance from generation 

 to generation. 



At intervals of about four weeks and associated in some 

 way with the menstrual period of the female, an ovum, 



FIGURE 8 



Four large structures are shown in this diagram of the human female pelvis, viewed from the 

 side. The lower vertebra of the spinal column I; the lower bowel (rectum) II; the uterus 

 (womb) III; the vagina or vestibule leading to the outside IV; the bladder V. 



sometimes one from each ovary, breaks through its follicle 

 on the surface of the ovary and is drawn into the enlarged 

 end of the oviduct or fallopian tube (Figure 7) by the cur- 

 rents set up by the many little ciliated, or whip-like cells 

 which line the tube and its mouth. At any moment after 

 entering the tube the ovum may encounter sperm cells which 

 have made their way slowly through the uterus and up the 



