648 ABSORPTION. 



as true chyle, for the reason, that they observed similar globules in 

 artificial digestions; and, on the other hand, never detected them in the 

 digestive secretions. In their view, consequently, chyliferous absorption 

 is confined to the separation of chyle, ready formed in the intestine, 

 from the excrementitious matters united with it. But we must have 

 stronger evidence to set aside the overwhelming testimony in favour of 

 an action of selection and elaboration by the absorbents of all organ- 

 ized bodies vegetable as well as animal. The nutriment of the vege- 

 table may exist in the soil and the air around it; but it is subjected to 

 a vital agency the moment it is laid hold of, and is decomposed to be 

 again combined to form sap. A like action is doubtless exerted by the 

 chyliferous radicles; 1 and hence all the modes of explaining this part 

 of the function, under the supposition of their being passive, mechanical 

 tubes, are inadequate. Boerhaave 2 affirmed, that the peristaltic motion 

 of the intestines has a considerable influence in forcing chyle into 

 the mouths of the chyliferous vessels; whilst Dr. Young 3 is disposed to 

 ascribe the whole effect to capillary attraction; and he cites the lachry- 

 mal duct as an analogous case, the contents of which, he conceives, 

 and we think with propriety, are entirely propelled in this manner. 



The objections to these views, as regards the chyliferous vessels, are 

 sufficiently obvious. The chyle must, according to them, exist in the 

 intestines ; and, if that of Boerhaave were correct, we ought to be able 

 to obtain it from the chyme by pressure. As the chyle is not present, 

 ready formed, in the intestine, the explanations by imbibition and by 

 capillary attraction are equally inadmissible. There is no analogy 

 between the cases of the lachrymal duct and the chyliferous vessels ; 

 even if it were admitted, that the latter have open mouths, which is 

 not the case. In another part of this work, it was affirmed, that 

 the passage of the tears through the puncta lachrymalia, and along 

 the lachrymal ducts, is one of the few cases in which capillary attrac- 

 tion can be invoked, with propriety, for the explanation of functions 

 executed by the human frame. In that case there is no conversion 

 of the fluid. It is the same on the conjunctiva as in the duct; but, 

 in the case of the chyliferous vessels, a new fluid is formed: there 

 must, therefore, have been an action of selection exerted; and this 

 very action would be the means of the entrance of the new fluid into 

 the mouths of the lacteals. If, therefore, we admit, in any form, the 

 doctrine of capillary tubes, it can only be, when taken in conjunction 

 with that of the elaborating agency. " As far as we are able to judge," 

 says Dr. Bostock, 4 "when particles, possessed of the same physical 

 properties, are presented to their mouths (the lacteals), some are taken 

 up, while others are rejected ; and if this be the case, we must con- 

 ceive, in the first place, that a specific attraction exists between the 

 vessel and the particles, and that a certain vital action must, at the 

 same time, be exercised by the vessel connected with, or depending 



1 F. Arnold, Lehrbuch der Physiologie des Menschen, Zurich, 1836-7 j noticed in Brit.and 

 For. Med. Review, Oct., 1839, p. 479. 



2 Prelect. Academ. in Prop. Instit. Rei Med., 103. 



3 Medical Literature, p. 42, Lond., 1813. 

 < Physiology, edit, cit., 622, Lond., 1836. 



