THE INTESTINES. 



477 



The nerves are from the solar plexus ; they form a submucous plexus 

 (Meissner's plexus) and a mtjenteric plexus {Auerbach's plexus), comi^vmed between 

 the two planes of jhe muscular tunic. 



Numerous microscopic ganglia are found on the course of these plexuses. 



Development. — The small intestine appears at an early period in the foetus, 

 and during the foetal existence of Ruminants preserves a very remarkable 

 predominance over the large intestine — a predominance equally marked in the 

 vessels it receives ; for in a foetus of five months, we have found the collective 

 arteries of the small intestine equivalent to about ten times the volume of those 

 of the caecum and colon. 



Functions. — It is in the small intestine — under the influence of the hepatic, 

 pancreatic, and intestinal secretions — that are carried on those transformations 



Fig. 280. 



Fig. 281. 



HORIZONTAL SECTION THROUGH THE MIDDr.E PLANE OP 

 THREE PEYERIAN GLANDS, SHOV?ING THE DISTRIBU- 

 TION OF THE BLOOD-VESSELS IN THEIR INTERIOR. 



DIAGRAMMATIC REPRESENTA- 

 TION OF THE ORIGIN OF THE 

 LACTEALS IN A VILLUS. 



e, Ceutral lacteal ; d, connec- 

 tive-tissue corpuscles with 

 communicating branches; 

 c, ciliated columnar epithe- 

 lial cells, the attached ex- 

 tremitins of which are di- 

 rectly contiguous with the 

 connective tissue corpuscles. 



that constitute the digestive function. It is also in this intestine that the 

 absorption of the nutritive prmciples and fluids commences, and in which the 

 villi are the essential organs. 



2. The Laege Intestine. 



The large intestine commences by a vast reservoir in the form of a cul-de-sac^ 

 named the cmcum. It is continued by the colon, the posterior extremity of which 

 is succeeded by the rectum. It is separated from the small intestine by the ileo- 

 cecal valve. 



A. C^cuM (C^cuM Caput Coli) (Figs. 282, 283). 



Situation — Direction. — This is a very wide and elongated sac, occupying the 

 right hypochondriac, where it affects an oblique direction downwards and back- 

 wards. 



33 



