Buffering Value of American Peptones. 



17 



exhibit as much as five times more buffering action than another 

 peptone at the same hydrogen ion concentration. In general, the 

 peptones tested showed the highest degree of variation in buffering 

 effect in the zone of the hydrogen ion concentration limited be- 

 tween P H = 9 and P H = 8, and the lowest degree of variation in 

 the zone between P H = 4 and P H = 5- As to the absolute con- 

 centration of buffering salts, these were found in most peptones to 

 be the highest at the zone of the lowest concentration of the 

 hydrogen ions and not in the zone of neutrality or of high hydrogen 

 ion concentration where the buffering action would be most de- 

 sirable for the use in media for identification of bacteria. 



Below is a table showing the relative buffering action of pep- 

 tones at various P H levels. 



Peptone. 



PH 



Ph 



Ph 



Ph 



Ph 





9-8. 



8-7. 



7-6. 



6-5- 



5-4- 



Difco 



9 



5 



3-5 



5 



ii 





II 



8 



4 



5 



15 



Witte 



6 



6 



5 



4-5 



10 



Aminoid 



34 



ii 



7 



6 



14 



Fairchild 



12 



8 



9 



7 



14 



Roche 



13 



8 



S 



4 



10 





20 



ii 



9 



7 



12 



This work is a part of the investigation of food poisoning, con- 

 ducted under the direction of Dr. M. J. Rosenau, Professor of 

 Preventive Medicine and Hygiene, Medical School of Harvard 

 University. The investigations are made under the auspices of 

 the Advisory Committee on the Toxicity of Preserved Foods of the 

 National Research Council, and under a grant of the National 

 Canners' Association. 



9.(1756) 



Some mathematical relations in the Wassermann reaction. 



By STERNE MORSE. 



[From the Psychiatric Institute, Ward's Island, New York City.] 



Von Krogh's 1 equation, y = x n /(x n + k), has not received the 

 the consideration by immunologists which its very close statement 

 of the facts in several immune mechanisms capable of numerical 



1 Von Krogh, Journal of Infectious Diseases, 1916, xix, 452. 



