THE NATURAL HISTORY OF THE KANGAROO. 
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actively suck. The mother therefore places it upon one of its 
long and slender nipples (the end of which is somewhat swollen), 
this nipple entering its mouth, and the little creature remaining 
attached to it. The mother then, by means of the cremaster 
muscle (before spoken of), squeezes its own milk gland, and 
so injects milk into the young, which would thus be infallibly 
choked but for a noticeable peculiarity of its structure, admi- 
rably adapted to the circumstances of the case. 
Fig. 3. 
1 . Dissected Head of young Kangaroo. 
Elongated larynx. b, Cavity of mouth. 
2. Nipple of Mother. 
In almost all beasts, and in man also, the air-passage or 
windpipe (which admits air to and from the lungs) opens into 
the floor of the mouth, behind the tongue and in front of the 
opening of the gullet. Each particle of food, then, as it passes 
to the gullet, passes over the entrance to the windpipe, but is 
prevented from falling into it (and so causing death by choking) 
by the action of a small cartilaginous shield (the epiglottis). 
This shield, which ordinarily stands up in front of the opening 
into the windpipe, bends back and comes over that opening 
just when food is passing, and so, at the right moment, almost 
always prevents food from 66 going the wrong way.” But in 
the young kangaroo, the milk being introduced, not by any 
voluntary act of the young kangaroo itself, but by the in- 
jecting action of its mother, it is evident that, did such a 
state of things obtain in it as has been just described, the 
result would be speedily fatal. Did no special provision exist, 
the young one must infallibly be choked by the intrusion of 
milk into the windpipe. But there is a special provision for 
the young kangaroo ; the upper part of the windpipe (or 
larynx), instead of lying as in us, and as in most beasts, widely 
separated from the hinder opening of the nostrils, is much 
raised. It is in fact so elongated in the young kangaroo that it 
rises right up into the hinder end of the nasal passage j which 
embraces it. In this way there is free entrance for air from 
the nostrils into the windpipe by a passage shut off from the 
cavity of the mouth. All the time the milk can freely pass to 
the back of the mouth and gullet along each side of this elon- 
