300 DIGESTION. 



albumen and casein would be absorbed in far too small a quantity 

 from the intestinal canal to suffice for the nutrition of the 

 organism. 



An observation made by Bidder and Schmidt,* although not 

 very accurately carried out in all its details, may serve to give 

 further support to the above view. These experimentalists have 

 repeatedly observed that the contents of the thoracic duct did not 

 coagulate for several hours, and then only imperfectly, in dogs in 

 which the pancreatic duct had been closed for a long time, whereas 

 ordinarily these contents become coagulated in a few seconds. 

 Will not this result, if its connexion with the absence of the pan- 

 creatic juice in the intestine be confirmed by further investigations, 

 serve to demonstrate that the pancreatic juice itself exerts an 

 action on the metamorphosis of the peptones even after their 

 resorption into the lacteals, and that it probably contributes in 

 some degree to the regeneration of certain albuminates from the 

 peptones ? At all events, this observation is in perfect accordance 

 with the result of our experience, that the albumen-like bodies, as 

 emulsin, diastase, &c., are not capable of resorption, as well as 

 with the view, which we have boldly maintained, that the albu- 

 minates in their unchanged condition are only resorbed in an 

 extremely small quantity, the greater part of them being previously 

 converted into peptones. 



We are as little able to explain the reason why special vessels 

 exist in the organism for the resorption of the digested protein- 

 bodies arid their derivatives (that is to say, their peptones) as to 

 recognise the physical conditions which direct these substances, 

 although not exclusively, yet chiefly, to the lacteals in preference 

 to the blood-vessels. To speak candidly, we must confess that we 

 have no definite idea of the mechanism of resorption through the 

 lacteals. All experiments made with the view of explaining the 

 process of absorption by the lacteals, refer solely to the mechanism 

 of the continuous motion of the fluids in them, but not to the true 

 process of absorption. After having formerly determined all the 

 incidental or indirect means by which the motion of the chyle and 

 of the lymph is effected the special Vis a tergo which does not 

 admit of a physical definition we at length find Brucke'sf dis- 

 covery of fibre-cells in the intestinal villi (a fact which has been 

 confirmed by KollikerJ), affording a sufficient indication regarding 



* Op. cit. p. 259. 



t Berichte d. k. k. Akad. d. Wiss. zu Wien. 1851. 



$ Zeitscli. f. wiss. Zool. Bd. 3, S. 106 ; and Mikrosk. Anat. Bd. 2, S. 158. 



