296 



EDEMA 



is an exudate or a transudate. 1 According to Rzentkowski, 2 the 

 transudates at the moment they pass out of the vessels are 

 simply solutions of crystalloids in water and quite free from 

 proteid ; the small amount of proteid found in transudates he 

 ascribes to proteid pre-existing in the tissue-spaces. This idea 

 is hardly acceptable in view of the known permeability of the 

 vessel-walls for proteids in normal conditions ; more probably 

 in cardiac and renal dropsies the quantity of proteid escaping 

 from the vessels is not greatly different from normal, but the 

 excessive fluid escaping in these conditions carries with it no 

 additional proteids, and to this extent transudates in statu nas- 

 cendi are proteid-free. 



Transudates, even when produced by the same cause, vary in 

 composition in different parts of the body, presumably because 

 of variations in the permeability of the vessels in different 

 vascular areas ; just as pleural, pericardial, peritoneal, and 

 meningeal fluids normally differ from one another. Thus C. S. 

 Schmidt 3 found the composition of the transudates in different 

 parts of the body of a patient who died of nephritis to have the 

 following composition : 



TABLE III. 



As in this case, the general rule is that while the proportion 

 of salts remains nearly constant, the proportion of proteid in 

 edematous fluids in different localities varies in decreasing order 

 as follows: (1) pleura; (2) peritoneum; (3) cerebrospinal ; 

 (4) subcutaneous. In the last-named location the specific 

 gravity of edematous fluids may be as low as 1.005, and the 



1 Kivalta (Kif. Med., 1903; Biochem. Centr., 1904 (2), 529) has suggested 

 the following test to distinguish exudates and transudates : Into a beaker con- 

 taining 200 c.c. of water with 4 drops of glacial acetic acid, let fall a few drops 

 of the fluid to be tested. If an exudate, a bluish-white line is left transiently 

 behind the sinking drops, due to precipitation of the euglobulin and pseudo- 

 globulin. Memmi (Clin. Med. Ital., 1905, No. 3) suggests the larger content 

 of lipase as a means of distinction of exudates. Tedeschi (Gaz. degli. Osped., 

 1905 (26), 88) states that egg-albumen fed in large amounts appears in trans- 

 udates and not in exudates, and can be detected by the biological precipitin 

 test. 



2 Virchow's Arch., 1905 (179), 405. 



3 Hoppe-Seyler's Physiol. Chemie, p. 607. 



