176 INTRODUCTION. 



moment of its birth it is placed, by the mother, in her pouch ; conducted 

 to the nipple, to which it firmly adheres by the mouth, and continues 

 attached until developed to a considerable size. 



The Cetacea, in general, produce only one young at a birth ; but 

 their period of gestation is not known. The Quadrumana produce one, 

 sometimes two, at a birth ;* the period of gestation, in such species as 

 have afforded an opportunity of determining the time, is seven months. 

 Nine months is the usual term of gestation in the human race ; one, some- 

 times two (very rarely more), are produced at a birth ; and, in a state of 

 utter helplessness, requiring, for many months, the mother's unremitting 

 care. The long infancy, the. slow growth, and the late maturity of Man, con- 

 stitute a marked and important line of separation between him and all the 

 lower animals ; and materially influence his moral and social state of being. 



All the lower animals produce their young at that particular season of 

 the year most advantageous to the welfare of the offspring, and of the 

 parents : hence is the season of sexual association confined within re- 

 stricted periods : of the human species, the instinctive desires are solely 

 under the control and direction of his reason. 



It need scarcely be said, that the young of all Mammalia are, at first, 

 nourished entirely by the milk secreted in the mother's breasts. The 

 breasts, teats, or mammae, are conglomerate glands (that is, a mass com- 

 posed of smaller glands, compacted together), invested with cellular tissue ; 

 they are traversed by lactiferous tubes, communicating with each other, and, 

 ultimately, merging in canals, which lead to the nipple (composed of a 

 vascular tissue, and sensitive), there to open by several orifices. The 

 situation of the mammae varies in different animals ; they are pectoral, 

 ventral, or inguinal ; and their number has reference to that of the young 

 produced at a birth, In the human species, in the Simiae, in the Lemurs, 

 and Bats, and, also, in the Elephant, the mammae are two and pectoral. 

 In the Ruminantia they are either two or four, and inguinal, or, in the 

 groin ; in the Horse, and its allies, the mammae are two, and inguinal. 

 The Sow has from ten to twelve mammae, in pairs, along the abdomen. 

 Carnivorous animals have from six to ten ventral mammae, in pairs. They 

 are ventral and numerous in the Rodentia. 



The period of lactation, or suckling, is regulated by the growth of the 

 young, and the earlier or later development of their powers ; at first they 

 are fed exclusively with the mother's milk, but, in due time, they begin 

 to partake also of the food which is to constitute their aliment when adult. 

 Among the Carnivora, it is long before the young can procure their own 

 prey ; and it is not until after some weeks have elapsed, that they are 

 capable of taking other nutriment than that afforded by their parents; 



* The Jacchus penicellatus (or Oustiti) produces two at a birth ; and so, most probably, do the 

 allied species. 



