LACTEAL*. 67 



hour or two after eating, we shall observe a great num- 

 ber of extremely small vessels arising by imperceptible 

 orifices from the surface of the mucous membrane, and, 

 from the milky appearance of the fluid contained in 

 them, called lacteals. As they pass off from the intes- 

 tines, they unite together and form larger trunks ; these 

 proceed backwards towards the spine, where they meet 

 with a number of irregularly shaped bodies, called the 

 mcsenteric glands, in which they are ramified to extreme 

 minuteness. From these glands, come out several ves- 

 sels larger than the lacteals, but very similar to them in 

 appearance. These at last join in one common trunk, 

 Galled the thoracic duct. This vessel is about the size 

 of a goose-quill ; it lies along the spine running from the 

 abdomen up through the chest, till it terminates in one of 

 the veins of the left arm. To recapitulate in one sen- 

 tence the course of the chyle ; it is taken up from the 

 small intestines by the mouths of the lacteals ; carried by 

 them to the mesenteric glands, where some change with 

 which we are not yet acquainted, is wrought upon it ; 

 thence into the thoracic duct, which at last pours it into 

 the veins, where it becomes mingled with the mass of the 

 blood. 



Emily, You speak of the chyle being absorbed by 

 the lacteals, as if they exercised a sort of intelligence in 

 the process. I do not exactly comprehend your idea. 



Dr. B. The principles upon which the lacteals se- 

 lect the chyle from the mass of heterogeneous materials 

 with which it is mixed, have been variously explained 

 by physiologists. In this respect, the lacteals seems to 

 be analogous to the fibrils of the roots in plants, which 

 absorb from the soil those substances only which are 

 proper for the nourishment of the plant. We witness 

 the fact, but in attempting to explain it, we can go no 

 farther perhaps, than to attribute it to the operation of 

 vital, not mechanical principles. Such is a general 

 sketch of Digestion in man and a few other animals that 



