( 374 ) 



ccptiblc iiiÜueiice. This result was obtained not only with NaCl-solu- 

 tion, but also with grape-sugar and with mixtures of serum and water. 



Seeing this difference in the results, obtained with the same 

 sort of epithelium, (mly two possibilities suggested themselves: either 

 the method of investigation was not to be relied on, oi' the epithe- 

 lium, though drawn in the different cases from the same spot, was 

 not always in the same condition. 



The first possibility had to be rejected; 1. because in one and 

 the same experiment the results with salt-solutions of different con- 

 centration corresponded, not only two to two, but also mutually, and 

 that, indifferently whether the result did, or did not, indicate an 

 influence on the volume ; 2. because the method with the red and 

 the white corpuscles, the spermatozoa, and also with the bladder- 

 and oesophagus-epithelium obtained hij scraping, had yielded uniform 

 results. 



There is nothing left but to assume that the epithelium is not 

 ahvays in the same state of permeabiliti/. 



With respect to this we may form two conjectures: we may sup- 

 pose that it is merely a question of time, in other words, that in 

 those cases in which the volume of epithelium appears to be influ- 

 enced by the concentration of the salt-solutions, the cells after half 

 an hour's immersion are not yet, or but very imperfectly saturated 

 with the solution, whereas the osmotic equilibrium has already been 

 established. Under these circumstances more salt-solution might, 

 after half an hour's action, have penetrated into the cell, and the 

 concentration of the salt-solution would in a less degree cause its 

 influence to be felt on the volume of the cells. 



This, however, proved not to be the case. 



Consequently we must consider the secimd possibility, viz, that we 

 have to do with a modification in the state of the epithelium which 

 continues till it is removed by some agent, a chemical one, for instance. 

 And indeed, we sometimes succeeded in bringing epithelium from 

 one state into the other; and that, by means of Mg SO4, which is 

 known to be able to bring about a modification in the resorbing 

 power of the intestine, and also by the addition of traces of an acid. 

 I say purposely „sometimes", for now and then we failed. 



For the rest, the conditions under which the intestinal epithelium 

 passes from one state to another and what changes, the cell thereby 

 undergoes, have hitherto remained uidtnown to us ^). 



1) 1 may liere observe that this result is by no means a contradietiou of the views 

 I formeily exjoressed, viz, that the resorption phenomena, hitherto known, may be 

 explained physically. At the time I stated emphatically : //I do not think of asserting 



