392 



INDEX OF BACTERIAL MUTATION 



Variations in the Agglutination Optimum of Type G. 



Table V indicates that the agglutination optima of various strains 

 of Microbe G are not as strictly uniform as those of the parent D 

 type. One of the causes of this variation is passage of the microbe 

 through the animal body. An example of this variation was observed 

 during an attempt to cause reversion of Microbe G to the parent D 

 form. 



The Type G strain in question was characteristically of very low 

 virulence. 1.0 cc. of a serum broth culture, injected intrapleurally, 

 was required to produce fatal infection of a 600 gm. rabbit. The 

 organism recovered at necropsy of this animal was cultured and in- 

 jected into a second animal, and so on. At the third animal passage 



TABLE VI. 

 Effect of Animal Passage on Acid Aggluiinability of Type G. 



the virulence had greatly increased, 10~^ cc. of a serum broth culture 

 being fatal. But the organism, far from returning to the uniformly 

 turbid growth character of the Type D form, became more intensely 

 granular in its growth. This characteristic was so marked that 

 difficulty was experienced in preparing the washed suspensions for acid 

 agglutination test. 



The acid agglutination reaction of Type G strain after animal 

 passage was compared with the same strain which had been trans- 

 planted in parallel in serum broth. The Na acetate-acetic acid 

 buffer series was used. The culture was incubated at 43°C. for 

 16 hours (Table VI). 



It wiU be seen from Table VI, first, that much less hydrogen ion 

 is required to produce complete flocculation, and second that the 

 optimum is very greatly broadened. It has been widened from 



