294 DIGESTION. 



epithelium cannot be regarded as in a normal condition without 

 this layer of germs, other investigators, and especially Kolliker,* 

 Bidder and Schmidt, f and Frerichs,J look upon these vesicles, as 

 well as the branching lacteals of the villi, only as masses infiltrated 

 into the spongy parenchyma, and consider that these vesicles, 

 whether filled with refracting or granular matters, possess no true 

 walls. Bruch adopts this view in a memoir which he has very 

 recently published, and shows that in all probability the branch- 

 ing lacteals winning towards the margins of the villi are merely 

 blood-vessels, which are able to resorb fat during the process of 

 digestion equally well with the lymphatics. 



As there has hitherto been much uncertainty regarding the 

 morphologico-objective facts connected with the resorption of fat, 

 so also has there been much obscurity and controversy in the 

 views that have been brought forward regarding the mechanical 

 processes by which the transition of the fat from the intestine into 

 the lacteals and blood-vessels is effected ; and the reason of this 

 will be readily understood when we take the following points into 

 consideration. The animal body is everywhere permeated by an 

 aqueous fluid ; the fats are, however, absolutely insoluble in water 

 and aqueous solutions ; hence they cannot undergo diffusion in the 

 ordinary sense of the word, and the irresistible evidence of daily 

 experience demonstrates that oily fluids cannot penetrate through 

 membranes moistened with water. Viewing the case chemically, 

 we may say, that the fats are, in a certain sense, somewhat easily 

 decomposable ; but independently of the circumstance that stronger 

 reagents are necessary for this decomposition than we are accus- 

 tomed to find in the intestine, a closer investigation shows us 

 that the fat found in the lacteals is in precisely the same condition 

 as that which is contained in the chyme, and, consequently, that 

 the assumption that the fat is decomposed during its resorption 

 through the lacteals is inadmissible. We are led, therefore, to the 

 view, that certain special cells in each of the villi are solely devoted 

 to the absorption of fat ; the appearance of some transparent vesicles 

 filled with fat, and of other opaque ones distended with granular 

 matter, seeming to confirm this view. The chemist who is in the 

 habit of separating the fats from aqueous fluids, sometimes by a 

 filter saturated with water, and sometimes by one saturated with oil, 



* Mikrosk. Anat. Bd. 2, S. 163. 



t Op. cit.,p. 230. 



J Uaudworterb. d. Physiologic. Bd. 3, Abt. 1, S. 854. 



Zeitsch. f. wiss. Zool. Bd. 4, S. 282-298. 



