338 J. HOWAKD MUELLER 



HgS04 precipitate by HgS04, or precipitation bj^ Ag2S04 and 

 baryta. 



7. So far as has been learned, knowTi amino acids will function 

 in place of neither of these fractions. 



8. The silver sulphate precipitate or X fraction does not de- 

 pend for its activity on the pigment. It escapes precipitation 

 by phosphotungstic acid under certain conditions, but is readily 

 destroyed by this reagent. 



9. The silver sulphate filtrate, or Y fraction contains a con- 

 siderable quantity of a new sulphur containing amino acid, the 

 relation of which to the active Y has not yet been demonstrated. 



REFERENCES 



Dakin 1918 Biochem. Jour., 12, 290. 



Funk 1920 Proc. N. Y. Pathol. Soc, 20, 119. 



Mueller 1920 Proc. Soc. Exper. Biol, and Med., 18, 14 and 225. 



Mueller 1922 Jour. Bact., 7, 309. 



