226 COLLOIDS IN BIOLOGY AND MEDICINE 



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sheep. These became edematous, not only if the veins were ligatured, 

 but also if the artery was tied. Under the circumstances, an in- 

 creased blood pressure as the result of congestion need not be con- 

 sidered. Indeed, all dead bodies or portions of them which certainly 

 are without blood pressure swell up when immersed in water. 



It was thus demonstrated that the development of edema de- 

 pended upon the increased capacity of the tissues to swell, and the 

 question then presented itself, What change in the tissues permits the 

 development of edema? 



An explanation was provided by the studies of F. HOFMEISTER, his 

 pupils and successors, upon the swelling capacity of gelatin and re- 

 lated substances (see pp. 67-68). We learned in that chapter that 

 acids and alkalies increase swelling capacity, that other electrolytes 

 in the order there mentioned, either favor or diminish swelling, while 

 nonelectrolytes, as far as appropriate studies as yet show, have only 

 slight influence. MARTIN H. FISCHER* (in collaboration with 

 GERTRUDE MOORE) was able to demonstrate that the same laws 

 governed the swelling capacity of fibrin, the swelling of frogs' 

 muscles and the extirpated eyes of oxen and sheep. This explana- 

 tion presupposes no membrane or osmotic pressure; it permits an 

 unstrained interpretation of processes which otherwise are explained 

 with great difficulty in the case of animal cells unprovided with 

 membranes. 



The further question now presents itself, What electrolytes are re- 

 sponsible for the altered swelling capacity of the tissues in edema? 

 We can no longer offer a single explanation, and we must study indi- 

 vidual cases. 



Edema fluid, the C02 of which has been removed, is acid to 

 phenolphthalein; F. HOPPE-SEYLER found in it valeric, succinic, 

 butyric and lactic acids. STRASSBURG and R. EWALD found that the 

 C0 2 content of edema fluid was greatly in excess of that of venous 

 blood. 1 Of especial value is the discovery by F. ARAKI and H. 

 ZILLESSEN that any lack of oxygen is followed by an excessive 

 production of acid, though this fact may not be demonstrable by 

 indicators. 



One answer is thus given to the question asked above. Increased 

 acid production, one of the results of deficient oxygen, may cause the 

 development of edema. Such a condition occurs in circulatory dis- 

 turbances and in cardiac insufficiency, where edema is especially fre- 



1 I wish to point out that a certain contradiction is contained in the simul- 

 taneous presence of organic acids and increased CCV Possibly this may be 

 attributed to the fact that various edema fluids have been examined and un- 

 justified generalizations deduced. (The author.) 



