OEDEE OE MAESUPIALS. 
IV 
seizing them with her lips. This is how she proceeds in this opera- 
tion : applying her two fore-paws with force to the sides of the pouch, 
she drags these sides in opposite directions, so as to distend them 
and enlarge the opening, as we do when we untie a small bag or 
purse. She then introduces her muzzle into the pouch, and lying 
on the ground, so as to be in the most favourable position, she 
extracts the foetus, which has passed through the first phase of its 
existence. Then, without its ever using its members, she places it 
over one of her mammae, which it would be powerless of itself to 
reach, and holds it there till it has seized the teat. Arrived at 
this point, the young one has no further need of its mother’s 
assistance ; it adheres firmly to the teat, and cannot be separated 
from it unless some external violence is used. Nevertheless, its 
strength is not yet sufficient to render it capable of self-sustenta- 
tion ; that is to say, it is as yet incapable of sucking in the milk 
by which it is to be nourished. To prevent this from causing the 
young one to waste away and die of starvation, the female is pro- 
vided with a muscle, which, by contracting on the teat, causes the 
milk to be injected into its mouth. From what is stated above, 
we see that the essential difference between the Marsupials and the 
other Mammalia consists in their young requiring a mammary 
nourishment at a much less advanced period of their development. 
The marsupial bones, and the purse supported by these bones, are 
the consequences of this necessity. 
During the second period of gestation, the organization is com- 
pleted ; the new creature approaches more and more to its perfect 
form and final state of development. In the larger Kangaroos, the 
hair appears in the sixth month. From the beginning of the eighth 
month, the young Kangaroo puts its nose frequently out of doors, 
that is to say, protrudes its head from the marsupial purse, and as 
a prelude to its approaching independent existence, nibbles here 
and there the tender grass. At last it makes its entrance into the 
world, and ventures a few timid jumps, as it follows its mother. It 
begins now to live on its own responsibility ; but for some time it 
will return to its former hiding-place, either to find there a place 
of refuge in case of danger, or by its mother’s milk to make up 
for the insufficiency of the nourishment which its weak state has 
allowed it to procure. So one may see sucking at the same time great 
young ones almost emancipated, and weak creatures the produce of 
c 
