314 Fische/ s Theory of Edema [Dec. 



periments to be capable of a distinctly greater swelling than the ordinary 

 gelatin. (Page 109.) 



In passing let it be noted that this simple Observation teaches how a 

 chemical change, in this case induced through a ferment, in the colloid 

 itself — just such a change as might occur in Hving matter — may affect 

 its affinity for water, This is a fact not without biological significance 

 in this problem of the ways and means by which a tissue regulates its 

 water content. (Page 109.) 



The last paragraph in the above quotation is among the most 

 pregnant in Fischer's bock. If he had gone farther along this line 

 he would have noted previous observations of similar character^^ 

 and might then have given more attention to the influence of 

 enzymes as possible factors of importance in the development of 

 edemas. 



I do not know enough either of collochemistry or of edema to 

 add anything material to the superficial remarks I have already 

 made. Yet it may not be amiss to conclude with the direct Sug- 

 gestion that Fischer's deduction that acids as acids are the cause of 

 abnormal colloidal hydrophilia in animals does not necessarily fol- 

 low from any of his information. If his theory of the direct causa- 

 tive influence of acid in the production of edema is sound, it seems 

 to me its correctness still remains to be shown. There is much that 

 looks like analogy and coincidence in Fischer's presentation of the 

 case, but little that resembles positive evidence of primary direct 

 acid causation of edema under biological conditions. 



Perhaps I can emphasize my skeptical view by leading our 

 thoughts into a non sequitur similar to the one into which Fischer 



'^ Berg and Gies have found that colloidal water absorption is facilitated by 

 some hydrolytic enzymes (proteases). Journal of Biological Chemistry, 1907, ii, 

 PP- 508, 522, and 545. Among our conclusions on this point is the following one 

 (P- 545) • " Bloating influences on fibrin were due primarily to the acid or base, 

 but were more pronounced in the presence of enzyme. Elastin did not swell 

 perceptibly in either the acid or basic Solutions employed, but did so in the latter 

 when trypsin was present." Similar results were subsequently obtained in pre- 

 liminary experiments with collagen. Under the head of swelling effects on fibrin 

 we wrote (p. 523) : " We intend to repeat the experiments under various con- 

 ditions and to discuss the significance of the results after more data have been 

 accumulated." This intention has not been executed, although, like many others 

 which have been replaced by more urgent plans, we expect to follow it at an 

 early opportunity. 



