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. VIVIPAROUS ANIMALS. 



Quadrupeds alone are truly viviparous. The manner 

 in which the foetus is 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 ovum or germ, and 

 bring it to maturity. For this purpose, the germ is pro- 

 duced in the ovarium, 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 testicks. These, 



