SEC. 9. THE LACTEALS AND THE LYMPHATIC 



SYSTEM. 



285. We have seen that absorption does, or at least may, 

 take place from the stomach. We have also stated that a large 

 absorption, especially of water, occurs along the whole large intes- 

 tine. Nevertheless it is during the transit of food along the 

 small intestine that the largest and most important part of the 

 digested material passes away from the canal, partly into the 

 lacteals, partly into the portal vessels. The portal vessels are 

 simply parts of the general vascular system ; the lacteals, into 

 which we may at once say the greater part of the fat passes, are 

 similarly parts of the general lymphatic system, being in fact the 

 lymphatic vessels of the alimentary canal, and especially of the 

 small intestine. The only reason for the special name of lacteals 

 is that, unlike the lymphatic vessels of other parts of the body, 

 the lymphatics of the intestine contain at times a fluid of a 

 milky white appearance. Hence for the better understanding of 

 absorption by the lacteals it will be desirable to study at some 

 length the whole subject of the lymphatic system. 



The lymphatic vessels may be said to begin in minute 

 passages, possessing special characters, known as lymph-capil- 

 laries. Broadly speaking these lymph-capillaries are found, 

 in the mammal, in all parts of the body in which connective 

 tissue is found ; and they have special connections with those 

 minute spaces in connective tissue which we have already more 

 than once spoken of as lymph-spaces. Of all the varied functions 

 of connective tissue perhaps the most important is this relation 

 to the lymphatic system ; in nearly every part of the body 

 connective tissue serves as the bed or origin of lymphatic vessels. 



These lymph-capillaries, which, as we shall see, are frequently 

 arranged in plexuses, are continuous with other passages also 

 minute but of a different and more regular structure, the 

 lymphatic vessels proper, which are gathered into larger and 

 larger vessels, all running like the blood vessels in a bed of 

 connective tissue, until at last all the lymphatic vessels of the 



F. 31 



