282 Fischer's Theory of Edema [Dec. 



Having become familiär with the effect of various external condi- 

 tions on the swelling of two simple so-called hydrophilic or emulsion 

 colloids (fibrin and gelatin), we have now at our disposal some facts 

 which we may utilize in an attempt to analyze the ways and means by 

 which tissues hold their normal amount of water, and to discover how 

 under altered external conditions they may come to hold more or less 

 than is considered normal. It is clearly evident that could we show that 

 the same conditions which make fibrin or gelatin take up and give off 

 water affect protoplasm similarly, a real step forward in the Solution of 

 this Problem of the absorption and secretion of water by the tissues 

 would be made. This can be done and with great simplicity. As the 

 following paragraphs show, the absorption of water by muscle or the 

 absorption of water by the eyeball is entirely analogous to the absorp- 

 tion of water by fibrin or by gelatin. (Page 56.) 



From the results of his experiments in the latter connections 

 Fischer draws the following conclusions : 



The absorption of water by muscle is determined, in the main, by 

 the State of the colloids contained in the muscle. . . , The absorption 

 of water by the eye is governed by the same laws as the absorption of 

 water by fibrin or gelatin. (Page 74.) 



Discussing " the biological significance of the analogy between 

 the absorption of water by certain colloids and the absorption of 

 water by muscle and the eye," Fischer amplifies his views by allud- 

 ing, in the following terms, to the " pressure theory," the " osmotic 

 theory " and to cell " membranes " : 



We need not here again point out the fatal argument against the 

 pressure theory contained in the observations which show that enor- 

 mous amounts of water may be absorbed in the entire absence of a 

 circulation — a muscle absorbing more than twice its weight of water 

 in a dilute acid ; and a beef eye, enough to rupturethe enormously thick 

 and tough sclera. The forces displayed here are so great that they 

 cannot even be approximated by simple blood pressure. (Page 87.) 



If the cells obey the laws of osmotic pressure, then it is demanded 

 that in Solutions of different substances having the same osmotic pres- 

 sure the volume of the cells shall be the same. Exceptions to this 

 conclusion are the rule with cells. . . . There is little reason for accept- 

 ing the osmotic theory as of paramount or even great importance in 

 the explanation of the ways and means by which tissues absorb or 

 secrete water. (Pages 90 and 91.) 



