350 IVAN C. HALL 



color. Six lots of 100 cc. each were separated and to each was 

 added the amount of N/1 NaOH shown in table 3, and the total 

 volume of each lot was then equalized at 110 cc. by addition 

 of distilled water. The various media were tubed, sterilized 

 in the autoclave at 10 pounds for 30 minutes, slanted, and dried 

 at 37° C. for six days. Inoculation was made from 24 hour 

 testicular infusion agar cultures; incubation was at 37°C. and the 

 usual control tests confirmed the purity of the growth observed. 



It may be seen that "excellent" results may be expected be- 

 tween the limits of actual titre to phenolphthalein from below 

 + 1.7 to +3.2 Normal acidity. There will be found little if 

 any difficulty in the reaction when adjustment is made by addi- 

 tion of N/1 NaOH as if the acidity were to be reduced to a titre 

 of zero. It will still be found sufficiently acid, thanks to the 

 phosphate, to obviate the difficulty of caramelization. 



PEPTONE 



The recent scarcity of Witte's peptone has necessitated experi- 

 ments upon the substitution of an American product. These 

 have shown "Difco" peptone of the American Digestive Fer- 

 ments Co., Detroit, Michigan, to be equal to Witte's for this 

 purpose. 



VIABILITY 



In contrast with the experience of Vedder (1915) with starch 

 agar, prolonged viability cannot be claimed for cultures of gono- 

 cocci upon testicular infusion agar. It was found that daily 

 transfer of several strains for two weeks was eminently success- 

 ful; planting every other day failed to keep some of the strains 

 alive for more than four transfers and in all of these there was 

 evidence of deterioration. 



Inoculating testicular infusion agar as well as ascitic agar, 

 starch agar, ''salt free" veal agar or blood agar from another 

 medium we have often found it necessary to coax the growth 

 by repeated transfers and especially by respreading, before the 

 maximum crop could be obtained. For this reason much em- 

 phasis should be placed upon the importance of personal experi- 



