INDOL PRODUCTION 25 



It is stated that after a growth of from four to six weeks human strains show a dry 

 scale-like growth which is easily detached from the sides of the flask, while bovine 

 cultures show a sort of mucoid growth adhering to the walls. 



Egg Broth. This has been extensively used in the war zone for growing anaerobes. 

 Emulsify one whole egg in 300 c.c. water. Bring slowly to a boil with frequent 

 shaking. Then tube and sterilize. The organism of malignant cedema grows par- 

 ticularly well in it. 



CALCIUM CARBONATE BOUILLON 



Where we wish to cultivate such organisms as streptococci and pneumococci in 

 massive cultures we may add small fragments of marble (calcium carbonate) so 

 that any inimical excess of acid may be neutralized. North used a glucose bouillon 

 containing calcium carbonate in the production of massive cultures of B. bulgaricus. 



GLYCERINE BOUILLON 



Add 6% of glycerine to ordinary bouillon. It is chiefly used in the cultivation of 

 tubercle bacilli. 



PEPTONE SOLUTION (DUNHAM'S) 



Dissolve i% of Witte's peptone and K% of sodium chloride in distilled water. 

 Filter, tube, and sterilize. Peptone soluTioiTmay be used as a base for sugar media 

 instead of bouillon. If is themedium used in testing for indol production. This 

 test is made by adding from 6 to 8 drops of concentrated H 2 SO 4 to a twenty-four- to 

 forty-eight-hour-old peptone culture of the organism to be tested. If the organism 

 produces both indol and a nitroso body, we obtain a violet-pink coloration, "cholera 

 red." If no pink color is produced on the addition of the sulphuric acid, add about 

 i c.c. of an exceedingly dilute solution (i : 10,000) of sodium nitrite. 



Cholera Red. It is very important in determining the "cholera red" reaction 

 to know that the peptone used will give the reaction as it is not given by true 

 cholera strains with certain samples of peptone. 



For the Voges-Proskauer Reaction. Fill fermentation tubes with a 2% glucose 

 Dunham's peptone solution and sterilize. After inoculation with the organism to be 

 tested incubate for three days. Then add 2 to 3 c.c. of strong caustic potash 

 solution. The development of a pink color on exposure to the air is a positive reac- 

 tion (the color of a weak eosin solution). 



Hiss' SERUM WATER MEDIUM 



Take one part of clear beef erum and add to it about three times its bulk of 

 water. Heat, the mixture in the ?Ernold for fifteen minutes to destroy any diastatic 

 ferment which might be present. Color to a deep transparent blue with litmus 

 solution and then add i % of any of the various sugars used in fermentation tests. 

 Sterilize in the Arnold by the fractional method. 



