28o Fische/s Theory of Edema [Dec. 



General Statement. Fischer's theory of edema is summed up 

 in his recent book on the subject as follows •} 



A State of edema is induced whenever, in the presence of an ade- 

 quate supply of water, the afifinity of the colloids of the tissues for 

 water is increased above that which we are pleased to call normal. The 

 accumulation of acids within the tissues brought about either through 

 their abnormal production, or through the inadequate removal of such 

 as some consider normally produced in the tissues, is chiefly responsible 

 for this increase in the affinity of the colloids for water, though the 

 possibility of explaining at least some of the increased affinity for water 

 through the production or accumulation of substances which affect the 

 colloids in a way similar to acids or through the conversion of colloids 

 having but little affinity for water into such as have a greater affinity, 

 must also be borne in mind. (Page 99.) 



Preliminary observations. The first of his series of experi- 

 ments, and one of his fundamental observations, is thus described 

 by Fischer: 



The cause of edema resides in the tissues, A very simple experi- 

 ment proves this fact. If one leg of an ordinary frog {Rana), a tree 

 frog (Hyla), or a toad (Bufo), is ligated just above the knee as tightly 

 as possible, so that the ligature shuts off not only the venous flow, but 

 also the arterial, and the animal is then placed in sufficient distilled 

 water to cover the legs, the ligated leg develops an intense edema, while 

 the unligated one remains normal. To explain this result recourse can- 

 not be had in this experiment to the pressure of any circulating liquids, 

 for none such exists, and so all the conceptions of edema which regard 

 the pressure, per se, of circulating liquids, as one of the causes, or the 

 Chief cause, in the development of this condition, are robbed of their 

 most fundamental support. (Page 11.) 



At the conclusion of his description of several such experiments 

 Fischer adds : 



It is clear that the cause of edema resides in the tissues themselves, 

 and that these become edematous not because water is forced into them, 



* Fischer: Edema— a study of the physiology and the pathology of water 

 absorption by the living organism, being the 1909 Nathan Lewis Hatfield Prize 

 Essay of the College of Physicians of Philadelphia. 1910. Pp. 209. Wiley & 

 Sons, New York. A preliminary statement of his theory, and the experimental 

 findings on which he bases it, were published by Fischer in Kolloidchemische 

 Beihefte (Ergänzungshefte zur Kolloid-Zeitschrift), 1909-1910, i, p. 93- 



