92 rLAll-r FACTS FOR OLD AND YOUNG 



The fully developed zoosperms are suspended in a 

 transparent, gelatinous fluid, which, mingled with the 

 secretion of the prostate gland and other fluids which 

 it meets during its expulsion from the body, constitutes 

 the semen. 



The Ovum.— The female element of generation, the 

 ovum, is produced by an organ called the ovary, of 

 which there are two in each individual. In size and 

 form, the ovary closely resembles the testicle. Like 

 the latter organ, also, it is formed within the body early 

 in the process of development; but instead of passing 

 outward and downward, as does the testicle, it remains 

 within the abdominal cavity, suspended in place by lig- 

 aments. It is connected with a duct, which receives the 

 ovum as it is discharged, and conveys it to the uterus. 



The human ovum varies in size from one two hun- 

 dred and fortieth to one one hundred and twentieth 

 of an inch in diameter, and consists of a single cell. 



Ovulation.— Ova are not formed in such large 

 numbers as zoosperms. As a general rule, in the 

 human female, a single ovum is developed and dis- 

 charged once in about four weeks, during the period 

 of sexual activity. This view is disputed by some 

 physiologists, who claim that ovules are constantly be- 

 ing formed and thrown off, not only during that period 

 of a woman's life during which child-bearing occurs, 

 but prior and subsequent to the child-bearing period. 

 The development of the ovaries is symmetrical in all 

 the higher classes of animals, with the exception of 

 birds, in whom the right ovary is usually atrophied or 

 undeveloped, allowing room for the egg produced by 

 this class of the animal kingdom. 



Fecundation.— It is often asked, and the question 

 has elicited some discussion, Which is the principal 



