530 Bulletin 167 



Without enumerating the details of the minor differences 

 observed with the several strains the characteristics on this 

 medium may be summarized as follows: Alkali production and 

 more or less complete reduction of litmus occurred with all strains. 

 With the exception of strains CXL, CXLL CXLII, CXLHI, 

 CXLVI, XVI, XXXIII, XXXVIII, L, LI. and LIV, alkali was 

 produced promptly in the surface layer which soon cleared, 

 changed to acid and became more or less green in color. The 

 alkali layer diffused slowly downward, several well defined strata 

 often being differentiated. Digestion proceeded slowly with the 

 enumerated strains, and the medium gradually became more and 

 more blue, changing to purple at the time digestion became 

 evident. 



8. Gelatin colonics. — A rather superficial examination of 

 the colonies of all strains on gelatin showed that they were very 

 much alike. Liquefaction occurred quickly in all strains except 

 CXL, CXLI, CXLII, CXL1II, CXLVI, CXLVIL XVI, XXX! 1 1. 

 L, LI, and LIV. For complete description of the types of colo- 

 nies, see detailed characteristics of individual strains, pages 567- 



9. Agar colonies. — There were no essential differences 

 between the agar colonies of the several strains. For descrip- 

 tion of types, see detailed characteristics of individual strains 

 pages 568-570. 



10. Cohn's nutrient solution. — Tins medium was made ac- 

 cording to the following formula: 



Distilled water, 1000. cc, 



Di-potassium phosphate, 5. gr. 



Magnesium sulphate, 5. " 



Ammonium tartrate, 10. 



Potassium chlorid, 0.5 " 



All strains were tried on this medium several times, but 

 only two strains, LI and LIV, showed growth. These grew 

 well with fluorescence, and the growth was accompanied by the 

 formation of crystals of magnesium ammonium phosphate. The 

 development was gradual but persistent, fluorescence and crystals 



