390 PHILOSOPHY OF ZOOLOGY. 
for mutual impregnation: others have the sexual organs 
separate, and on different individuals. The young of 
such animals are either nourished at first by the store of 
food in the egg, or by the circulating juices of the mother. 
Those species in which the former arrangement prevails 
are termed Oviparous, while the term Viviparous is restrict- 
ed to the latter. As the organs of reproduction are dis- 
played in the greatest perfection in those animals with dis- 
tinct sexes, we shall proceed to consider, 
I. Vivirarous ANIMALS. | 
Quadrupeds alone are truly viviparous. The manner 
in which the foetus 1s nourished previous to birth, the pe- 
culiar configuration of the sexes, and the nature of the-re- 
productive organs, indicate an arrangement for the genera- 
tion of quadrupeds to which there is nothing analogous 
among the rest of living beings. 
Before entering upon the consideration of the structure 
of the peculiar organs employed, and their functions, it is 
scarcely necessary to remark, that it is the business of the 
Female, in all animals, to prepare the ovowm or germ, and 
bring it to maturity. or this purpose, the germ is pro- 
duced in the ovariwm, farther perfected in the uterus or 
matrix, and finally expelled from the system through the 
vagina. The office of the Male is to impregnate the germ 
by means of the spermatic fluid. This fluid is secreted in 
the testicles, transmitted by the spermatic ducts, and finally 
conveyed by the external organ to its ultimate destination. 
In proceeding to our account of the reproductive organs in 
viviparous animals, we shall first consider those which are 
peculiar to the male sex, and afterwards those by which 
the female is characterized. 
1. Male Organs.—The spermatic fluid is secreted in 
two glandular bodies which are called the testicles. These, 
