OF THE DEOLUTITIOK. 
59 
ceive the eggs, is enlarged and terminated by a fringed 
border at its anterior end ; this canal descends straight 
towards the anus, and terminates by a wide opening in the 
bottom of the cloaca, below the valve which separates that 
cavity from the rectum. 
The testicles^ of a variable form in different species of 
Ophidians, are of a deeper colour than the kidneys. The 
vasa deferentia go out from the internal surface of the tes- 
ticles ; in making numerous little turns, they descend along 
the external edge of the kidneys, and are adherent through 
their whole extent to the ureters ; approximating on the 
back of the cloaca, they perforate the walls common to this 
cavity and the ureters, and open into the mouths of these 
last, which are indicated, as we have already stated, by a 
conical elevation. The mouths of the vasa deferentia are 
so delicate that they are only perceptible in serpents of a 
large size, — a circumstance which renders anatomical re- 
searches very difficult, because we can neither inflate the 
organs, nor pass a probe, on account of their convoluted 
structure, 
or THE BEOLUTITIOX. 
The manner in which snakes swallow their food is very 
simple. They always commence at the head of their prey, 
which they receive into their mouth ; while the teeth fasten 
themselves on one side of their prey to hold it fast, the op- 
posite jaw advances, and the teeth engage themselves in 
the victim, and draw it inwards. By this alternate play of 
the jaws, during which the principal part is performed by 
the lower jaw, the deglutition is effected, after efforts more 
or less great according to the volume of the prey. It is 
also for the same object that the jaws dilate, in order to 
render the swallow more capacious : during this act, the 
serpent discharges an abundant saliva on its prey, which it 
renders more slippery, and more easy to be swallowed. 
When the animal they attempt to swallow is too large, they 
are unable to introduce it into their maw until a consider- 
able time has elapsed. Serpents found in this state offer 
a hideous spectacle ; the disgust which they thus inspire, 
