NATURAL HISTORY. 109 



" That natural affection, so connatural to all or most creatures 

 toward their young, what an admirable, noble principle it is, 

 implanted in them by a wise Creator ! " DERHAM. 



the mammalia, not excepting those which come into the world blind 

 and naked. The pouch answers as a description of second womb, 

 in which the young animals are brought to maturity. 



338. The young of all the animals of this order are remarkable for their imperfect 

 development at the time of their birth. Even in the species without pouches (for 

 some have a mere fold of the skin, scarcely visible) the young hang under the belly 

 of the mother for a certain time ; then they mount on her back, and twist their tai j 

 round hers to fix themselves. The young of the kaola, which has no tail, fixes 

 itself on the parent's back, and fastens there with its hands. It is remarkable that, 

 in the unpregnant animal, the pouch is closed, being glued, as it were, to the body 

 of the parent by a peculiar secretion. As the pregnancy advances, this secretion 

 becomes absorbed, and the folds of the pouch are set free, so that just at the time 

 when the young within the body of the animal are prepared to leave it, the pouch 

 or nursery on the outside is fitted to receive them.* 



339. Why are the young of these animals lorn in such a helpless 

 condition ? 



Because by far the greater number of the marsupial animals are 

 either leapers or climbers ; and this peculiar arrangement of 

 the organs of gestation is evidently intended to enable the 

 Joins to have more powerful action than they could have if the 

 body of the animal were encumbered with full-grown young. 



340. It has not hitherto been noticed by naturalists (the Author believes) that the 

 peculiar gestation of the marsupialia forms an intermediate design between the 

 complete gestation of mammalia and the egg-laying capacity of birds. To animals 

 of flight, bearing their young, apart from any consideration of the number of the 

 offspring, must be a serious impediment ; they are, therefore, endowed with tht 

 power of excluding the ova and maturing their young apart from their own bodies, 

 To animals that are terrestrial, and endowed with leaping powers, the encumbered- 

 womb must prove almost as great an impediment as to creatures of the air. The 

 gestation, therefore, is imperfect, and is completed after the young has passed from 

 the womb. It is also worthy of remark that as birds lay from two to fifteen ot 

 eighteen eggs, marsupial animals bear from one to twelve young ones. 



The pouch of the opossum is thus described by M. D'Argaza: " The female 

 has the whole length of the belly cleft or slit, and appearing like a person's waist- 

 coat buttoned only at the top and bottom. This cavity the animal has the power of 

 firmly closing. Within it are thirteen teats, extremely small, one in the centre and 

 the rest ranged round it." The same authority speaks of one which he saw that 

 had thirteen young ones. They had ceased to suck, and the pouch, since they were 



Cavier's " Regne Animal." 



