VARIATION OF SALMONELLA PULLORUM 37 



Table 10. — Results obtained with chicks exposed to normal and variant 



strains of 5 1 . pullorum. 



*Six control chicks were not destroyed. 



Few colonies were isolated from the second chick, all of which appeared atypical 

 in colonial and cellular morphology. (See Figures 44-47, inclusive.) 



Variant Vl-a was recovered on meat extract agar, and resembled the normal 

 type. Liver infusion agar plates were negative. As stated earlier, this variant 

 does not present a very marked colonial difference from the normal. 



Strain IV was recovered from four out of seven chicks. Few gross lesions were 

 observed. In every case the organism was isolated from the spleen, while cultural 

 tests with other tissues were negative in most instances. The colonial and cellular 

 morphology on plain extract agar appeared typical, while on liver infusion agar 

 a rough colony type which contained pleomorphic cells was observed. (See 

 Figures 48-51, inclusive.) 



Strain XIV was recovered from five out of seven chicks. Gross lesions were 

 observed in most instances, involving one or more of the following organs: — liver, 

 spleen, and heart. The recovered organism exhibited a smooth colony type on 

 meat extract and liver infusion agars in most instances. This strain, while ex- 

 hibiting a tendency to vary, generally appears quite typical. (See Figures 52-59, 

 inclusive.) 



The chicks infected with Strain 11,706 manifested clinical symptoms of the 

 disease. Upon necropsy extensive lesions were observed, and the organism was 

 recovered from six of the seven chicks. This apparently typical strain seemed to 

 be more pathogenic than the other variants employed. Meat extract agar plates 

 yielded typical growth, while on liver infusion agar a few colonies exhibited surface 



