26 
ON THE PHYSIOONOMY OE SEEPENTS. 
testine, that the same organs which in other vertebrata 
occupy one or more spacious cavities, are packed in Ophi- 
dians, on account of the elongated shape of their trunks, 
in a long, narrow cylinder. It is obvious that this dispo- 
sition could not have taken place without great changes in 
the formation of the viscera, and without disturbing bila- 
teral symmetry. On this account, the heart is sometimes 
far removed from, at other times approximated to, the 
head, according to the greater or less capacity of the sto- 
mach ; for the same reason, we often find but a single lung, 
sometimes before the heart, but generally placed behind 
that organ. This lung almost always terminates in a sort 
of sac, of greater or less size, serving as a reservoir for air. 
The form of the liver, for the same reason, is modified into 
a narrow riband, extending from the heart to the pylorus. 
The gaU-bladder, that it might not be impeded in its func- 
tions when the stomach is full, is removed from the liver, 
and is placed in the same curvature of the duodenum which 
receives the pancreas and the spleen. The stomach re- 
sembles a long, not very wide, cylinder. The intestines 
succeed, the numerous inflections of which are filled with 
fat, and, after descending in a straight line, terminate in the 
cloaca. The inferior part of the abdomen, not being suf- 
ficiently capacious to receive the other organs, is the cause 
of the anomalous position of the kidneys, the testicles, and 
the ovaries ; hence, the penis and the secreting organs are 
lodged in the tail. 
It is evident from what we have said, that the form of 
the greatest part of the internal organs of serpents has 
no influence on the exercise of their functions ; we shall 
afterwards even see that the position of these organs not 
only differs in different species, but sometimes varies among 
individuals of the same species. 
The disposition of the external organs, on the contrary, 
presents more constant forms ; but these parts are modified 
according as the species inhabit trees, the ground, or the 
water. Locomotion, however, is exercised very uniformly : 
the same movements make the snake glide on the ground 
which impel it through the depths of the humid element, 
or which serve to entwine it around the branches of trees. 
