240 DIGESTION. [CHAP. xxv. 



several fatty molecules of large size, readily distinguished by 

 their highly refractive power. The contrast between the epithelial 

 particles obtained from this flocculent matter, and those of the 

 intestine of an animal that had fasted for some time before death, 

 is very striking, and indicates that they undergo a change during 

 chylification, either connected with the absorbing process or with 

 the transformation of the alimentary substances. (Fig. 163). 



Of the peculiar mechanism by which this nascent chyle is intro- 

 duced into the lacteal vessels, and of the nature of the changes 

 which it undergoes in them to form perfect chyle, we can form no 

 adequate idea in the present state of our knowledge. We do 

 know, however, that the material before its entrance into the vessels 

 is very different from what it becomes after its introduction ; and 

 that in its advance towards the centre of the absorbent system it 

 undergoes further changes, all of which tend to assimilate it more 

 nearly to the blood itself. 



Of the Chyle. If, as seems most correct, we apply the term chyle 

 to the fluid contained in the lacteal vessels during and shortly 

 after digestion, we must make the distinction between white chyle 

 and transparent chyle. The white chyle is a milk-like fluid, 

 homogeneous in appearance, which, on being withdrawn from the 

 lacteals and allowed to stand, separates, as blood would do, into 

 serum and a clot. This clot consists of fibrine, which entangles, 

 by its coagulation, certain particles proper to the chyle. These 

 are chyle-corpuscle or globules, in every respect similar to lymph- 

 corpuscles, and an infinite multitude of particles of extreme mi- 

 nuteness, to which Mr. Gulliver has given the name of molecular 

 base of the chyle. These particles consist of fatty matter in a state 

 of extreme subdivision. 



During fasting, and also during the digestion of food wholly 

 devoid of fat, the fluid contained in the lacteals is perfectly trans- 

 parent and colourless, and not to be distinguished from the lymph 

 of the lymphatics. In this fluid there is no molecular base, while 

 all the other elements of the chyle are present. Hence there can be 

 no doubt that the white colour of the chyle is due to the presence 

 of the molecular base. 



The chyle may exhibit various degrees of milkiness, according to 

 the quantity of the molecular base. The white chyle, therefore, is 

 chyle with molecular base in greater or less quantity ; the trans- 

 parent chyle is devoid of molecular base. Both kinds of chyle 

 consist of a liquor chyli, essentially the same as the liquor sanguinis 

 holding suspended in it chyle globules in the transpareut-chyle, 



