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(indudiiirj the inlranuclcar) substances, is the same as in the cor- 

 respond uuj red blood- corpuscles. 



We may ask ourselves wlietlier we have not here to do with a 

 general phenomena which, consequently, also applies to the other cells. 



Before we are justified to answer in the aifirmative, we should 

 of course have to investigate a number of the other cells. Most of 

 them however don't admit of this. Cells such as the intestinal and 

 the trachealepithelium, which allow salt-solutions of all concentra- 

 tions to pass through them and thus neither contract nor dilate, are, 

 as is obvious, excluded. 



Sunniiarij. 



The pi'ineipal results to which the preceding investigation has led, 

 are as follow. 



T. Of the four kinds of epithelium examined, the intestinal-epithe- 

 lium and the ciliary epithelium of the trachea undergo no modification 

 of volume under the influence of Na Cl-solutions of different concen- 

 tration ; they allow the Na Cl-solutions easily to pass through them. 

 And this is the case, not only with the body of the cell, but pro- 

 bably also with the nucleus. 



II. The fixct, that the ciliary-epithelium, at the end of the expe- 

 riments, is found to be still alive, increase the value of the results, 

 not only with respect to the ciliary-epithelium itself, but also with 

 respect to the intestinal-epithelium. 



III. In contrast with the intestinal and the ciliary -epithelium, the 

 bladder- and oesophagus-epithelium exhibit a contraction by hypcr- 

 isotonic and a dilation by hypisotonic Na Cl-solutions. 



IV. From the amount of this contraction and dilation may be 

 calculated the proportion between the volume of protoplasma substance 

 and the intracellular contents. 



This proportion, for the oesophagus-epithelium as well as for the 

 bladder- epithelium, appears to correspond to that in the red blood- 

 corpuscles of the same animal. 



V. Urea- solutions, in contrast with Na Cl-solutions, leave the 

 volume of the isolated bladder-epithelium unaltered. From mixtures 

 of urea- and Na Cl-solutions indeed only the urea makes its way through 



