DIVISION OF THE INTESTINES. 45 



the lacteals, all these observers have agreed, that the orifices 

 which communicate with the lacteals are on the villi ; and 

 that these villi contain also very fine ramifications of blood- 

 vessels. They have also agreed that the surface of the intes- 

 tines in the intervals of the villi seems occupied with the 

 orifices of ducts or of exhalent vessels.* 



Division of the Intestines. 



Although there is a considerable degree of uniformity in the 

 structure of the intestinal canal, different parts of it are very 

 distinguishable from each other by their exterior appearance, 

 by their size, their investments, and their position. 



The first division is into two great portions, which are very 

 different from each other in their diameter and length, as well 

 as their situation ; the first portion being much smaller in diam- 

 eter, and near four times the length of the other. 



These portions are therefore known by the names of Great 

 and Small Intestines, and the line of separation between them 

 is very strongly marked ; for they do not gradually change 

 into each other, but the alteration in size and in exterior 

 appearance is very abrupt, and their communication is not 

 perfectly direct. A considerable portion of the Great Intestine 

 is fixed immovably in the abdomen, while a large part of the 

 Small Intestine is very movable. 



Each of these great portions of the intestinal tube is subdi- 

 vided into three parts. Thus, in the Small Intestine, there is 

 a piece at the commencement called Duodenum, a great part 

 of which has no coat from the peritoneum, and is immovably 

 fixed in one situation ; while all the remainder of the small 

 intestine has a uniform covering from the peritoneum, and is 



* On this subject the student will consult with adv^antage, Hewson's Experi- 

 mental Inquiries, vol. 2 ; Sheldon's History of the Absorbent System, part 1st ; 

 Cruikshank on the Anatomy of the Absorbent Vessels ; and the Historia Vaso- 

 rum Lymphaticorum Corporis Humani, of Mascagni. 



— The more recent investigations of Beclard, Meckel, Breschet, Muller, Dr. 

 Horner and others have a tendency to disprove the existence of absorbing 

 orifices on the surface of the villi ; vide, Absorbent System. — p. 



