328 



FEEDERICK A. WOLF AND I. V. SHUNK 



and about 4 per cent NaOH. When these media were examined 

 after having been maintained in an ice chest at about 10°C. for 

 twelve hours, all of those to which more than 1 cc. of NaOH 

 had been added were found to have become liquid, and a heavy 

 whitish precipitate had formed. All of the tubes to which HCl 

 had been added were still solid, however. All of the tubes 

 containing media which had remained soUd were placed in 

 boiling water until the media had liquified whereupon they 



TABLE 2 

 Effect of acid and alkali on solidification of gelatin 



were again cooled to 7.5°C. The alkaline gelatin again solidified, 

 but 1.5 cc. of HCl in 10 per cent gelatin and 1.7 cc. in 15 per 

 cent gelatin were now the limits of the jellifying power. 



DISCUSSION 



Manifestly, in the case of both agar and gelatin, strong acid 

 or alkali in the presence of high temperatures is capable of 

 destroying the jellifying power. Everyone who has made culture 



