ABSORPTION BY LYMPHATIC AND LACTEAL VESSELS 



241 



brane, and, with the alimentary substances proper, a large quantity of 

 secreted fluid is reabsorbed. This is particularly marked as regards 

 the bile. The biliary salts disappear as the alimentary mass passes 

 down the intestine and undoubtedly are absorbed, although they are so 

 changed that they can not be detected in the blood by the ordinary 

 tests. In this portion of the alimentary canal, it will be remembered, a 

 large absorbing surface is provided by the arrangement of the mucous 

 membrane in folds, forming the valvulae conniventes, and by the pres- 

 ence of villi, which are found throughout the small intestine. A cer- 

 tain portion of the gaseous contents of the intestines is also taken up, 

 although it is not easily ascertained what particular gases are thus 

 absorbed. 



ABSORPTION BY LYMPHATIC AND LACTEAL VESSELS 



Physiological Anatomy of the Lymphatic and Lacteal Vessels. The 

 lacteals are the intestinal lymphatics ; and during the intervals of intes- 



Fig. 50. Origin of lymphatics (Landois). 



I. From the central tendon of the diaphragm of the rabbit (semidiagrammatic) ; s, lymph-canals 

 communicating by x with the lymphatic vessel L ; a, origin of the lymphatic by a union of lymph- 

 canals; e, e, endothelium. II. Perivascular canal. 



tinal absorption they carry a liquid that is identical with the contents of 

 other lymphatic vessels. In their structure, also, the lacteals are identi- 

 cal with the general lymphatics. 



In the connective tissues which are so widely distributed in the 

 body there are always found irregularly-shaped stellate spaces, which 

 communicate with each other by branching canals, called lymph-spaces. 



