ALIMENTARY TRACT AND ITS APPENDAGES oll 
bends sharply to enter the descending limb of the second loop. 
This bend or duodeno-jejunal flexure (X, Fig. 179) is a relatively 
fixed point in the growth of the intestine, and marks the bound- 
ary between the duodenum and succeeding parts of the small 
intestine. The second loop descends deep into the umbilical 
cord, and the yolk-stalk is attached to its lowermost portion. 
A bilateral swelling at the upper end of its ascending limb is the 
primordium of the cecal processes, and marks the anterior end of 
the large intestine, which passes in a slight curve to the cloaca. 
In the subsequent growth of the intestine the fixed point 
referred to above at the hinder end of the duodenum is held in its 
place, and the duodenal loop in front of it simply becomes longer 
Fic. 180. — Viscera of a chick embryo of 17 days’ 
incubation from the right side. (After Duval.) 
Am., Attachment of amnion to umbilical stalk. 
Li. r.,]., Right and left lobes of the liver. Pe., Pan- 
creas. U.St., Umbilical stalk. Other abbreviations 
same as Fig. 179. 
without forming secondary convolutions; the pancreas comes to 
lie in this loop. The second loop, on the other hand, forms 
numerous secondary convolutions (Fig. 180) which lie at first in 
the umbilical cord, but which are gradually retracted (seven- 
teenth to eighteenth day) into the abdominal cavity. 
The two intestinal ceca begin to grow out as finger-shaped 
processes from the swelling already referred to, about the seventh 
day, and rapidly attain considerable length. The large intestine 
elongates only about in proportion to the growth of the entire 
embryo. 
Having thus noted the general gross anatomy of the embry- 
