ACTION OP THE SMALL INTESTINE. 609 



teals. Accordingly, at this part of the canal, chyliferous vessels are 

 first perceptible. 



The change effected upon the chyme in the small intestine is pro- 

 bably, like that produced on the food in the stomach, of an entirely 

 physical character. The chyle itself, we shall endeavour to show 

 hereafter, is formed by an action of elaboration and selection exerted 

 by the chyliferous vessels. No difference is observable between the 

 chylous and excrementitious portion of the chyme in any part of the 

 small intestine; nor can it be separated by pressure or by any other 

 physical process. M. Magendie, 1 indeed, has affirmed, that if the 

 chyme proceeds from animal or vegetable substances that contain fat 

 or oil, irregular filaments are observed to form, here and there, on the 

 surface, sometimes of a flat, at others, of a round shape, which 

 speedily attach themselves to the surface of the valvulse, and appear 

 to be brute chyle; but this is not observed when the chyle proceeds 

 from food, that does not contain fat. In this case, a grayish layer, of 

 greater or less thickness, adheres to the mucous membrane, and appears 

 to contain the elements of chyle. MM. Leuret and Lassaigne 2 state, 

 that if an animal be opened while digestion is going on, on the sur- 

 face of the chyme, between the pylorus and the orifice of the ductus 

 communis choledochus, a grayish-white, homogeneous, dense, fluid, and 

 acid substance is perceived on the villi of the intestine. Neither of 

 these, however, is chyle. It is merely the substance whence chyle is 

 obtained by the action of the chyliferous vessels. The fact, mentioned 

 by M. Magendie, regarding the appearance of irregular filaments, when 

 animal or vegetable substances, containing fat or oil, have been taken 

 as diet, has been the occasion of other erroneous deductions of a 

 pathological character. Frank 3 asserts, that he was requested to see a 

 prince, who was attacked with epilepsy. His physician, a respectable 

 old practitioner, assured Frank, that he could make his patient void 

 thousands of filiform worms at pleasure. As he was unable to define 

 either the genus or species of these worms, the quantity of which, from 

 his account, seemed to be prodigious, Frank requested to be a witness 

 of the phenomenon. The physician administered a dose of castor oil, 

 which produced numerous evacuations, containing thousands of whitish 

 filaments similar to small eels ; but on an attentive examination of 

 these pretended worms, they were found to consist entirely of the castor 

 oil, in a state of fine division. 



The alteration of the aliment in the small intestine is probably of a 

 chemical nature ; yet its essence is impenetrable. It has, accordingly, 

 been conceived to be organic and vital. The same remarks are appli- 

 cable here as were indulged upon the supposed organic and vital action of 

 the stomach exerted in the formation of chyme. The agents of this 

 conversion are: the fluids secreted from the mucous membrane of the 

 small intestine, and the biliary and pancreatic juices, aided by the tem- 

 perature of the parts, and the peristole. Haller 4 was of opinion, that 

 the first of these is a principal agent. Reflecting on the extensive 



1 Precis, &c., ii. III. 2 Op. citat. 



3 De Curandis Hoininum Morbis Epitome, lib. vi. p. 218. 4 Element. Physiol., xix. 5. 



VOL. i. 39 



