20 



ni*e excreted. This means an almost absolute retention of chlorine. 



Many theories have been suggested to account for this i-etention, 

 without a satisfactory explanation being an-ived at. Our investiga- 

 tions have shown that the chlorine percentage in blood and blood- 

 serum has fallen so mupli, tliat the kidneys can no longer withdraw 

 chlorine from the blood ^). The lower chloi'ine jiercentage of the 

 blood can oidy be explained by the supposition that chlorine is 

 retained by the tissues, and that it does not, as in normal circum- 

 stances, pass from the tissues into the blood. The question: "what 

 causes chlorine retention in febrile diseases" is, therefore, tui-ned 

 into another question: "why does not chlorine pass, in these circum- 

 stances, from the tissues into the blood ?" 



Is it because the permeahility of the tissue-cells for chlorine has 

 been modified? 



It is difticult to invest igcate the permeability of human tissue-cells, 

 even for anorganic substances. The only cells which admit of such 

 researches are the red blood-corpuscles. Hence we ha\e made use 

 of these cells. But before experimenting on this valuable material, 

 it was found desirable to in\'estigate various questions relating to 

 permeability, on the blood-corpuscles of animals. 



If the composition of the medium in which the red blood-corpus- 

 cles are suspended is altered, interchanges between red blood-cor- 

 puscles and their medium take place. Until now it has been found 

 possible to explain these interchanges, as an osmotic phenomenon^); 

 there was no need to assume that a change in the nature of the 

 surface of the red blood-corpuscles had taken place. It was even 

 found that an intentional modification of this surface did not modify 

 the osmotic interchanges. 



Hamburger, namely, found that an addition of chloroform to red 

 blood-corpuscles did not in the least atfect their resistance to diluted 

 salt-solutions '^). This result had not been expected by him. Indeed 

 there were grounds for assuming, that the lipoid snbstances, which 

 form at least part of the surface of the red blood-corpuscles, are 

 softened by chloroform. After this process this outer layer will offer 

 less resistance to the swelling caused by hypotonic solutions. Still 

 nothing of this decreased resistance was observed. And we too 

 could show, in accordance with this fact, that the interchange of 



1) I. Snapper, Dissertatie, Groningen 1913. 

 *) Hamburger, Osmotischer Druck. und lonenlehre. 

 S) Hamburger. Biologie der Phagozyten. 19 1 3, p. 199. 



This resistance of the red blood-corpuscles is a good criterion as regards their 

 permeability. 



