ELEMENTARY PHYSIOLOGY 



capillus, a hair) which originate in the organs and tissues of nearly 

 every part of the body. Those which have their origin in the 

 walls of the intestines differ from the others in that they contain, 

 during digestion, a fluid resembling milk in appearance. They 

 are consequently distinguished from the other lymphatic capil- 

 laries by the name lacteals. (Lat. lac, milk.) We now proceed 

 to study the nature and uses of these lacteals. 



Fig. 109. Lymphatics of the Head, Neck, Thorax, Ac. 



i and 2, the upper portion of the thoracic duct, showing its junction with the venous system. 



It will be remembered that the small intestine is lined inter- 

 nally by a mucous membrane which is characterised by a number 

 of minute hair-like projections called villi, giving the mem- 

 brane the appearance of a yellowish or pinkish velvet. Each 

 villus is supplied with a network of blood capillaries, and also 

 one or more lacteals. These vessels are very advantageously 

 situated for absorption, as they are surrounded on all sides by 



