224 BERTHA VAN H. ANTHONY AND C. V. EKROTH 



titration. The boiling titration figures are plotted as curve 

 a. The room temperature titration curve (a) comes so near 

 the desired reaction of plus one ( + 1) that even a mere glance 

 will suffice to convince one that the room temperature titration 

 approaches more closely the one per cent line, which is the acid- 

 ity we set out to secure. 



This was not surprising to us as our practical experience for 

 several years past had indicated such a condition. The modifica- 

 tion, (page 212), devised at that time and now further sub- 

 stantiated by these experiments, has proved to be so very useful 

 in its results that it is employed in these laboratories for nearly 

 all the routine preparation of some fifty different kinds of media, 

 aggregating over 8000 liters per year. 



STERILE SODA 



In order to avoid the complications of further hydrolysis 

 and precipitation after the addition of soda to a medium which 

 must later be sterilized, it has been suggested that sterihza- 

 tion be done first and that sterile soda be carefully added after- 

 ward according to the titration of samples withdrawn under 

 sterile conditions. This has been practised by some workers, 

 apparently with success. So far, in our laboratory, it has 

 shown no advantages in the production of diphtheria toxin 

 broth. Further work in this line is contemplated. 



AGAR 



When the need arose of supplying large amounts of neutral 

 veal agar for the growing of the gonococcus, streptococcus and 

 other organisms in bulk for antigens, difficulty was expericxiced. 

 To grow these organisms in large lots with unfailing success 

 is not always easy. Our trouble seemed due chiefly to the 

 reaction of the medium. Finally the modified titration method 

 was adopted for agar also. 



Since agar solidifies at a little below 40°C. the room temperature 

 titration was not suitable. At first any temperature between 



