ABSORPTION BY BLOOD-VESSELS OF VILLI. 



Fig. 205. 

 .2 x 



511 



Vessels of an intestinal vil'.ns 

 of a Hare, from a dry prepara- 

 tion by Dolimger : 1, 1, veins 

 filled with white injection; 2, 2. 

 arteries injected red. Magnified 

 about 45 diameters. 



A, apex of intestinal vil- 

 !us from the duodenum of 

 Human female ; B, a mesh of 

 the vascular net-work, 1, 1, 

 filled up with delicate cellu- 

 lar tissue, 2, magnified about 

 45 diameters. 



almost invariably the same ; being that to which the name chyle has been 

 applied. It appears from the uniformity of its composition, which forms a 

 striking contrast with the diversity of the food from which it is obtained, that 

 the lacteals (or rather the absorbent cells, amongst which they originate) have 

 in some degree the power of selecting the particles of which it is composed ; 

 and that, whilst they take up such a proportion of each class of alimentary 

 materials as will rightly blend with the rest in the nutritious fluid, they reject 

 not only the remainder, but also (for the most part at least) any other ingre- 

 dients which may be contained in the fluid of the intestines. Such may be 

 stated as the general result of the experiments that have been made to de- 

 termine their function ; though it is unquestionable that extraneous substances, 

 especially of a saline nature, occasionally find their way into this system of 

 vessels. This may not improbably be due to a correspondence in the size 

 and form of the ultimate particles of such substances, with those of the mate- 

 rials normally absorbed by the lacteals.* 



675. On the other hand, the Blood-vessels seem to be less concerned in 

 nutritive absorption, but take up from the alimentary canal a portion of almost 

 any fluid matters which it may contain. This seems to have been established 

 by the carefully-conducted experiments of MM. Tiedemann and Gmelin, who 



1 Experiments upon the function of Absorption in Plants, whose radical vessels have a 

 corresponding power of selection, appear likely to assist in elucidating this interesting subject. 

 By the experiments of Dr. Daubeny it has been ascertained, that if a plant absorb any par- 

 ticular saline compound, it can also be made to absorb those which are isomorphous with it, 

 though it will reject most others. See Princ. of C4en. and Comp. Phys., 294. 



