8G 
COMPARATIVE ZOOLOGY. 
the nostrils, and two from 
the ears; one from the 
windpipe, guarded, by 
the epiglottis; one from 
the mouth, with a fleshy 
curtain called the soft pal¬ 
ate ; and one from the 
oesophagus. It is the nat¬ 
ural passage for food be¬ 
tween the mouth and the 
oesophagus, and of air be¬ 
tween the nostrils and 
windpipe. Like the 
mouth, it is lined with a 
soft mucous membrane. 
The oesophagus is a 
long and narrow tube, 
formed of two muscular 
layers: in the outside one, 
the fibres run length¬ 
wise ; in the other, they 
are circular. It is lined 
with mucous membrane. 
While in all Fishes, Rep¬ 
tiles, and Birds the ven¬ 
tral chamber is one, in 
Mammals it is divided, 
by a partition called the 
diaphragm , into two cav¬ 
ities — the thorax, con¬ 
taining the heart, lungs, 
Fig. 51.—Digestive Apparatus of Man (diagram): 1, tongue; 2, pharynx; 3, (Esopha¬ 
gus ; 4, soft palate; 5, larynx; G, palate; 7, epiglottis; 8, thyroid cartilage; 9, 
beginning of spinal marrow; 10, 11, 12, vertebne, with spinous processes; 13, 
cardiac orifice of stomach; 14, left end of stomach ; 18, pyloric vaive; 19, 20, 21, 
duodenum; 22, gall-bladder; 27, duct from pancreas; 28,29, jejunum of intestine; 
30. ileum; 34, coecum; 36, 37, 38, colon, or large intestine; 40, rectum. 
