Cation in Precipitation of Proteins 91 



and spongiosa as well as the dorsalis penis artery of the dog are 

 supplied by nerve filaments belonging to the true sympathetic 

 system and not to the parasympathetic system. Full details to 

 appear in the Journal of Urology. 



45 (2005) 



The influence of the cation in the precipitation of the proteins 

 of blood by sodium phosphate. 



By PAUL E. HOWE. 



[From the Department of Animal Pathology of the Rockefeller 

 Institute for Medical Research, Princeton, N. J.] 



The precipitation of the globulins of blood with sodium sulfate 

 at 37° C. 1 indicates the presence of critical zones in the curve of 

 precipitation with increasing concentrations of sodium sulfate. 

 Comparison of the results obtained with sodium sulfate at these 

 zones with other procedures for the precipitation of the proteins 

 of blood, by other salts or acidification, showed similar quantita- 

 tive results. The critical zones occurred at 10. 6 2 , 14.2, 17.7 and 

 21.3 per cent, of anhydrous sodium sulfate, /. c, the designated 

 quantity of salt dissolved in 100 c.c. of water at 37 °C. These 

 values are approximately 0.75, 1.00, 1,25 and 1.50 molar solu- 

 tions of sodium sulfate. Furthermore, under similar conditions 

 any given concentration of salt will precipitate the same amount 

 of protein. These observations have been extended to other salts 

 and it has so far been found that a similar relationship holds for 

 each salt; after precipitation begins there is a constant difference 

 in the concentration of salt for the succeeding fractions. Precipi- 

 tation of fibrinogen ends at approximately the concentration of 

 salt found by Lewith 3 for the beginning of the precipitation of 

 euglobulin, — observations which were correlated on the basis of 

 equivalent concentrations by Hofmeister 4 . The difference in 

 concentration between the various fractions is not necessarily the 

 same for all salts, e.g., for magnesium sulfate it is 0.375 mol. 



1 Howe, Paul E., Jour. Biol. Chem., 1921, xliv, 93. 



2 Howe, Paul E., Jour. Biol. Clicm., 1922, liii, 479. 



3 Lewith, S., Archiv. f. Exper. Path. u. Pharm., 1887, xxiv, 1. 



4 Hofmeister, F., Archiv. f. Exper. Path. u. Pharm.. 1887, xxiv, 257. 



