64 ON THE PLACE OF MAN IN THE SCALE OF BEING. 



though in a very imperfect condition. Moreover, it has been satisfactorily 

 ascertained that the young are nourished, for some time after their birth, by 

 a mammary secretion, which the organization of their mouth at that period 

 enables them to obtain from the parent. In the Marsupialia, there is a 

 remarkable compensation for the abrupt termination of the period of uterine 

 gestation, the young being received into a pouch or marsupium, within which 

 the nipple is situated ; this is extremely prolonged, and the mouth of the foetus 

 (for so the being must still be regarded) is adapted to receive and hold on by 

 it; so that the little creature, which looks at first more like an earth-worm 

 than a Mammiferous animal, is thus suspended within the protective pouch, 

 until its development is so far advanced, that it can shift for itself in the same 

 degree as other new-born animals can do. 



45. The period of gestation in the higher sub-class of Mammalia, is usually 

 prolonged, until the foetus is able, on its entrance into the world, to execute 

 regular movements ; some of these being merely indicative of its desire for 

 food, and others evidently designed for the acquirement of it. In many species, 

 the young animal seems to be from the first in the full possession of its senses, 

 and has considerable power of active locomotion; in general, however, it is 

 very dependent upon its parent ; only being able to obtain food when this is 

 placed within its immediate grasp. Such is the case with the Human infant, 

 which is closely dependent upon its parent, during a larger proportion of its 

 existence, than is the young of any other animal. Here again, therefore, we 

 perceive the application of the general law, that, the higher the grade of 

 development a being is ultimately to assume, the more does it require to be 

 assisted during the early stages of its progress. In the case of Man, the pro- 

 longation of this period has a most important and evident influence upon the 

 social condition of the race; being, in fact, one of the chief means, by which 

 the solitary are bound together in families. 



46. The class Mammalia, taken as a whole, is not characterized so much 

 by the possession of any one particular faculty, like that which has been 

 seen in Birds, as by the perfect combination of the different powers, which 

 renders the animals belonging to it susceptible of a much greater variety of 

 actions, than any others can perform. There are none that can compete with 

 Birds in acuteness of sight ; but there are few that do not possess the senses 

 of smell, taste, and touch in a more elevated degree. There are none which 

 can rival Birds in rapidity of locomotion ; but there are few which cannot per- 

 form several kinds of progression. Several of their movements require a 

 considerable amount of flexibility in the spine ; hence the vertebral column, 

 and the bony framework of the trunk, are never so much consolidated as they 

 are in Birds. On the other hand, the neck is much less movable ; it never 

 consists of more than seven vertebra, and these are always present ; so that 

 they are sometimes of great length, as in the Giraffe, and sometimes ex- 

 tremely short, as in the Whale, which seems to have no neck at all. In the 

 greatest number of Mammalia, the body is supported upon all the four extre- 

 mities, as in Reptiles ; being adapted for progression along the surface of the 

 earth. There are some species, however, in which the typical structure has 

 undergone a metamorphosis, by which it is made to resemble that of a Bird ; 

 whilst in others it is modified, so as to conform to the character of the Fish. 

 In the Bats, the power of motion is almost entirely delegated to the wings, 

 which are composed of skin, stretched over a bony framework formed of the 

 widely-extended hand ; and the sternum has a projecting keel for the attach- 

 ment of the pectoral muscles, as in Birds. And in the Whale tribe, the power 

 of locomotion is almost completely taken from the extremities, and given 

 back to the trunk, as in Fishes ; for the posterior extremities are entirely ab- 

 sent, and the anterior serve only for guidance: there is this important differ- 



