CIRCULATORY SYSTEM 297 
follows: (1) The beak, or mandibles, for picking up feed and 
sometimes cutting or tearing it; (2) the gullet, through which 
feed passes, after being moistened in the mouth with saliva; (3) 
the crop, or temporary receptacle; (4) the stomach (proventriculus), 
where gastric juice is secreted and mixed with it; (5) the gizzard, 
a strong muscular sac, where, by means of small stones and sharp 
grit (serving as the teeth of the bird), the feed is ground more finely 
than in the mouths of many 
of the larger animals; and (6) 
the intestine, a long tube which 
receives the pulped material 
from the gizzard, subjects it 
to the action of several juices 
from the pancreas, the liver, 
and other glands, and absorbs 
the digested and dissolved por- 
tions; the undigested residue 
passes along to (7) the cloaca, 
where it mixes with the waste 
materials from the genito-uri- 
nary canal, which empties into 
the intestine at this point. 
Circulatory System.—The 
circulatory system of the fowl 
is very similar to that of mam- 
mals, being composed of a 
heart with four cavities, from 
which the blood is pumped to 
all parts of the body, through 
blood vessels, some of which 
convey nourishment, while oth- 
ers purify the body by carry- 
ing away its waste material. 
The blood of birds is about 
two or three degrees warmer Fig. 143.—Circulatory system of the fowl. 
than that of mammals. 
The circulatory system is composed of two distinct circuits or 
courses which the blood takes in passing through the body. The 
diagram (Fig. 148) shows the course of the blood. The heart is 
designed to pump two streams of blood at once, its left side pump- 
ing the blood through the body and the right side through the 
HEAD AND 
UPPER PART OF BODY 
ORGANS 
BODY AND 
LOWER EXTREMITIES 
