Note: In the column under "immunity" the " +" sign designates that the culture is 

 biologically distinct. 



8. DESCRIPTION OF THE TEST ORGANISMS: Six test organisms were 

 used: two hemolytic strains, two, green-producing and two, indifferent. 

 The members of each pair were not duplicated individuals of the same 

 type (see carbohydrate reactions). Moreover there was no duplication 

 of strain in the entire series (see agglutination reactions) . 



III. PREPARATION OF MASS CULTURES 

 i. MEDIUM: 



(a) Choice of Infusion basis: A comparative study of the different solid 

 media available for streptococcus cultivation shows that the organisms 

 accumulate more rapidly on some than on others. Five media were 

 considered . 



(1) Hemolyzed blood glucose veal infusion agar: The veal infusion 

 was prepared as described above diluted with an equal volume 

 of 3 per cent agar-agar solution and sterilized. When needed, 

 the agar was melted and cooled slowly to 43-45 C. Sterile 

 hemolyzed defibrinated blood (i volume blood to 2 volumes of 

 distilled water) and sterile 12% glucose solution were then 

 added. The proportion used was o.i c.c. of the diluted blood 

 and 0.25 c.c. of the sugar solution to every 3.0 c.c. agar. 



(2) Huntoon agar (56) . 



(3) Hasting gelatin-agar (57): The original directions are somewhat 

 vague. This description is our interpretation: One pound beef 

 meat in loooc.c. water was boiled for one hour, strained through 

 a wire sieve, made up to the original volume, 10 grams peptone 

 and 5 grams NaCl added and set in the Arnold sterilizer for 20 

 minutes. The infusion thus obtained was used as the solvent for 

 the 15 grams agar-agar and 20 grams gelatin added at this point. 

 Finally, enough NaOH was added to make the mixture neutral to 

 phenolphthalein, the medium being kept at the boiling point 

 during the titration. 



(4) Beef liver agar: 500 grams fresh hashed beef liver were infused 

 with 500 c.c. tap water for three hours at 55 C., strained through 

 a wire sieve, 10 grams peptone and 5 grams NaCl added and set 

 in the "Arnold" until solution was complete. The hydrogen-ion 

 concentration was adjusted to a PH value = to 7. 9. After being 

 mixed with 500 c.c. 3 per cent agar-agar solution, the infusion was 



