( 382 ) 



Solutions eniploved. 



Volume of the 

 epitbelium 



a. A'aCl-solutiou of 0.7° <, 



b. 75 cc NaCl-sol. of 0.7°/o + 25 cc ur. sol. isat. vitli NaCl 7°/o 



c. IS'aCl-solution of 1.5°/,, 



(/. 75 cc NaCl-sol. 1.57o + 25 cc ur. .sol. isot. with NaCl. ].5°/o 



85.5 

 102 

 61 

 70 



Had flic Na Cl-urea-solution h acted like the Isa Cl-solution a, 

 with which it was isotonic, the volume would then have become, 

 not 102, but 85.5. And had the Na Cl-urea-solution d acted like 

 the Na Cl-solutiou c, with which it was isotonic, the volume would 

 have become, not 70, but 61. 



But the volume of b corresjionds exactly to what would have 

 been found, if 75 cc. Na Cl-solution 0.7% had been diluted with 

 25 cc. of water, instead of with 25 cc of urea-solution. 



The same applies to d with respect to c. 



The urea has thus distributed itself equally over the cell and its 

 surroundings^ without curtailing the power of the epithelium to 

 resist Na CI. Foi' the calculation of the volume of protoplasma- 

 substance from a and b (supposing the urea-solution added, be con- 

 sidered as water) and from c and a give the same figures. 



We are, therefore placed before this question : What is the reason 

 the urea so easily enters the scraped - off epithelium, whereas the 

 intact wall of the bladder appears to exhibit if not an absolute, yet 

 but a very slight permeability to urea. 



With the answering of this question I am now engaged. 



IV. OESOPHAGUS-EPITHELIUM. 



We now Avish to examine another species of epithelium of which, 

 as was the case with bladder-epithelium, an impermeability to salt 

 was to be foreseen. 



For this purpose we tried the epithelium of the oesophagus, which 

 for resorption has no more significance than has the bladder. What 

 we scrape off here consists of great flat cells in which are found 

 no inconsiderable number of round and oval grains which make the 

 impression of being bacteria, and which may also be deeply stained 

 with alkaline coloring matter. 



The experiments performed in precisely the same way as those 



