200 THE VITAL FUNCTIONS. 



Chapter IX. 



LACTEAL ABSORPTION. 



The Chyle of which we have now traced the for- 

 mation, is a fluid of uniform consistence, perfectly 

 bland and unirritating in its properties; and the 

 elements of which have been brought into that 

 precise state of chemical composition, which ren- 

 ders them fit to be distributed to every part of the 

 system for the purposes of nourishment. In the 

 lower orders of animals it is generally transparent ; 

 but the chyle of Mammalia is more or less opaque, 

 from the presence of a multitude of globules, which 

 give it a white colour, like milli.* 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-t 



The chvle is absorbed from the inner surface of 

 the intestines by the Lacteals, which commence by 

 very minute orifices, in incalculable numbers, and 

 nnite successively into larger and larger vessels, till 

 they form trunks of considerable size. They pass 



* It is more white and opaque in carnivorous than in herbivorous 

 mammalia. It is also white in Reptiles and Fishes ; but ahnost in- 

 variably colourless in Birds. 



t Medico-Chirurgical Transactions, vi. 630. 



