( 375 ) 



Involuntarily we are reminded here of what Heidenhain observed 

 in the live animal with respect to the power of the interstitial sub- 

 stance between the epithelium cells to allow methyleneblue to 

 pass through it : in the same field he saw amidst cells whose inter- 

 stitial substance was coloured blue, others whose interstitial substance 

 had remained absolutely colouiless. ^). 



In the most recent times they have tried in the Zurich laboratory 

 to answer the question, whether in the intestine, besides the inter- 

 stitial substance situated between the epithelium cells, the cells them- 

 selves allow dissolved substances to pass through them. ") 



The investigations described above have, in my opinion, given an 

 answer to this question. For, save in those exceptional cases, in 

 which tiie scraped-off epithelium appears to be in a peculiar condition, 

 the volumina of cells, influenced by salt-solutions of different concen- 

 tration for half an hour, exhibit no mutual differences. 



Now this phenomena might be explained by the supposition, that 

 the epithelium cells are quite indifferent to the salt-solutions, that is 

 to say, that they allow neither water nor salt to pass through them ; 

 but the supposition that they would not allow water to pass through 

 them is immediately disproved by the fact that when, i mined iatel;/ 

 after mixing them with salt-solutions, we centrifugalize them, and 

 thus do not wait half an hour before doing so, a difference in volume 

 is distinctly observed, viz., the volume increases as the concentra- 

 tion rises. 



The cells then, must be permeable to water. Yet the fact, that 

 the volumina of the epithelium cells alter a longer immersion in 

 salt-solutions approach nearer and nearer to each other, forces us no 

 less to conclude that the salt-solution penetrates, as such, into the cell. 



Our experiments teach us something, also with respect to the 

 permeability of the cell-iiiiclens. They teach us that it is most pro- 

 bable that, beside the body of the cell, the cell-nucleus of the intestinal 

 epithelium also allows salt solutions to pass through it. For, just 



'/that life neitlier can, nor will exercise an influence on the resorption process." 

 //Under physiological and pathological conditions finely-shaded changes may iinques- 

 «tionably manitest themselves in living membranes, exercising no small influence 

 //on the physical process taking place in them, but by which these processes do not 

 /'cease to be purely physical." (On //The significance cf respiration and peristaltic 

 for the resorption in the intestine." Verslag der Verg. .Jan. i'.t^, 1896, note). 



') Heidf.nhain. 15eitrage zur Anatomie und Physiologic der Diinndarraschleirahaut. 

 Pfliiger's Arcliiv, Snpplemontheft. 1SS8, S. 49. 



") 1{. lloiiEE. Ueber Resorption im Büniulanii. Zweite Mittheiluiii;-. Plluger's 

 Archiv, B ?4, ï?. 269, ISiJ'.i. 



