Titration of Bacteriological Media 



By our results in I and II, we have shown that apparently 

 the length of time out of the body has a definite influence on the 

 virulence of the organisms. That the virulence may diminish 

 in the course of the disease is suggested by a single observa- 

 tion: A mouse was injected with the sputum of a case of in- 

 fluenza on the first day of the disease; it died 6 hours later with 

 positive cultures of B. influenza in the peritoneal exudate and 

 heart's blood; on the second day of disease, some more sputum, 

 smears of which showed numerous B. influenza, from this 

 patient was injected into a mouse; this mouse, however, did not 

 die for 48 hours, and at autopsy cultures from the heart's blood 

 and peritoneum were negative. 



Conclusions. 



1. The virulence of B. influenza is very variable and this 

 may have some bearing on the epidemiology of the disease in- 

 fluenza in man. 



2. A few observations are present that may throw some 

 light on the results of bacteriological studies of this disease. 



9 (1969) 



The formol titration of bacteriological media. 

 By J. HOWARD BROWN 



[From the Department of Animal Pathology of the Rockefeller 

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



The formol titration devised by Malfatti 1 (1908), Sorensen 

 (1907 2 , 1908 3 ), and by Henriques and Sorensen 4 (1909) for the 

 titration of the ammonia and amino acids of urine has been more 

 or less modified by bacteriologists for the titration of media and 

 cultures. Ammonium chloride reacts with formaldehyde to pro- 

 duce hexamethylentetramine and hydrochloric acid. Amino acids 

 and polypeptides react with formaldehyde to produce acid methy- 

 lene derivatives which are stronger acids than the amino acids 



1 Malfatti, H., Z. f. anal. Chem., 1908, xlvii, 273. 



2 Sorensen, S. P. L., Comptes-rendus des Travaux du Lab. de Carlsberg, 

 1907, vii, I. 



s Sorensen, S. P. L., Biochem. Zeitschr, 1908, vii, 45. 



* Henriques, V., and Sorensen, S. P. L., Z. f. physiol. Chem., 1909, lxiii, 27. 



