SUCKING OF INFANTS. 
349 
r The serous or peritoneal coat belongs only to that part of the canal 
which lies within the abdominal cavity. The intestinal tube, as well 
as the liver and spleen, is thrust, as it were, into the peritoneal sac, 
carrying before it a part of the membrane, which, after investing it, 
forms at its posterior border a double suspensory band or mesentery. 
Nearly the whole of the intestinal canal, with the exception of the 
duodenum, has a mesentery, or band of this kind. I have elsewhere 
pointed out,* that in the earliest stage of embryonic life the stomach 
likewise has a distinct suspensory band (a mesogastrium), which at a 
later period undergoes a remarkable change, being converted into a 
sac, the great omentum. It is not till the third or fourth month of 
fœtal life that the great omentum and transverse mesocolon become 
continuous. In many Mammalia,—as the dog, cat, hedgehog, rabbit, 
and horse,—there is no connection between the stomach and colon, 
the great omentum or mesogastrium in them passing backwards to 
be attached to the vertebral column without being connected with the 
mescolon, which arises from the vertebral column quite separately: 
and the same is the condition in the human embryo in the earlier 
stages of fœtal life. 
The omentum can perform no very important part in the function 
of the digestive organs, since in many animals it has not the same 
anatomical connections, and is represented merely by a loose band 
extending from the stomach. 
CHAPTER III. 
OF THE MOVEMENTS OF THE ALIMENTARY CANAL. 
The muscular coat of the alimentary tube is one of that series of 
contractile organs, of which the motion is involuntary and dependent 
on the sympathetic nerve. The cerebro-spinal nervous system has 
but a limited influence over it; but this influence is evidenced by 
manifold sympathies which exist between the digestive apparatus 
and the brain and spinal marrow. 
The commencement and termination only of the canal have 
muscles which are subject to cerebro-spinal nerves and the will; such 
as the muscles of the mouth, and the muscles moving the lower jaw 
and pharynx, for mastication and in part deglutition, on the one 
hand, and the mjiscles about the anus, for exoneration on the other. 
I consider it unnecessary to explain the movements of sucking, of 
the prehension of food, and of mastication. ( On these movements, 
see Treviranus, Biologie, t. iv. 311.) The internal causes of such 
instinctive motions as the sucking of new-horn children must remain 
enigmatical. It is difficult in this case to remain satisfied with 
Cuvier’s theory of “instinct;” viz. that animals still so young are 
* Meckel’s Archiv. 1830, page 395. 
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