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CHAPTER IX. 



LACTEAL ABSORPTION. 



THE Chyle, of which we have now traced the formation, 

 is a fluid of uniform consistence, perfectly bland and unirri- 

 tating in its properties, the elements of which have been 

 brought into that precise state of chemical composition which 

 renders them fit to be distributed to every part of the sys- 

 tem for the purposes of nourishment. In all the lower or- 

 ders of animals it is transparent; but the chyle of mammalia 

 often contains a multitude of globules, which give it a white 

 colour, like milk. Its chemical composition appears to be 

 very analogous to that of the blood into which it is afterwards 

 converted. From some experiments made by my late much 

 valued friend Dr. Marcet, it appears that the chyle of dogs, 

 fed on animal food alone, is always milky, whereas, in the 

 same animals, when they are limited to a vegetable diet, it 

 is nearly transparent and colourless.* 



The chyle is absorbed from the inner surface of the intes- 

 tines by the Lacteals, which commence by very minute ori- 

 fices, in incalculable numbers, and unite successively into 

 larger and larger vessels, till they form trunks of considera- 

 ble size. They pass between the folds of a very fine and 

 delicate membrane, called the mesentery, which connects 

 the intestines to the spine, and which appears to be inter- 

 posed in order to allow them that degree of freedom of mo- 

 tion, which is so necessary to the proper performance of 

 their functions. In the mesentery, the lacteals pass through 

 several glandular bodies, termed the mesenteric glands, 

 where it is probable that the chyle undergoes some modifi- 

 cation, preparatory to its conversion into blood. 



* Medico-Chirurgical Transactions, vi. 630. 



