426 ABSORPTION. 



shank, and others. Though these vessels are very delicate 

 and difficult of study, it is now pretty generally admitted that 

 they have no orifices at their origin in the intestines and other 

 parts, but are perfectly closed, and all substances which 

 are absorbed by them enter by imbibition. The old idea, 

 which dates from the discoveries of Asellius and Pecquet, 

 that the lacteals absorb all the products of digestion, was 

 overthrown by the experiments of Magendie, and of those 

 who experimented : after him on vascular absorption. It is 

 now known that the fatty portions of the food, reduced to a 

 very fine emulsion by the pancreatic juice, are absorbed by 

 this system of vessels, and that these are the only principles 

 which are taken up in great quantity. The arguments which 

 we have already mentioned are sufficient to establish this 

 fact. If the abdomen of a living animal be opened during full 

 digestion, then, and then only, will the lacteals and the 

 thoracic duct be found distended with fatty emulsion. If the 

 organ which digests fat be rendered incapable of performing its 

 function, the lacteals cease to carry chyle. These vessels do not 

 appear in the mesentery until the food has passed the orifice of 

 the pancreatic duct. Finally, the observations of Bouchardat 

 and Sandras remove all doubt as to the absorption of the pro- 

 ducts of the digestion of fatty matters by the lacteals ; for these 

 observers found not only that in dogs the proportion of fat in 

 the chyle was increased pari passu with an increase in the 

 quantity of fat taken as food, but that the particular kinds of 

 fat administered to the animals could be recognized in the 

 chyle. 1 We have seen that a certain quantity of fat escapes 

 the lacteals and is absorbed directly by the blood-vessels ; and 

 it becomes an important question to determine whether the 

 lacteals, in addition to their more prominent function, be not 

 concerned in the absorption of drinks, the albuminoids, saline 

 and saccharine matters, etc. This question will be taken up 



1 BOUCHARDAT ET SANDRAS, Recherches^ur la Digestion ct P Assimilation den 

 Corps gras. Anmiaire de Therapeutique, Paris, 1845, p. 242 et scg. 



