68 



Studies in Bacterial Variability. 



2. Both forms may be obtained from one and the same eu-agglutinable 

 strain of a bacillus, and both may revert, or may be converted mutually 

 the one into the other. 



3. In agglutination tests carried out in the ordinary manner, a highly 

 dys-agglutinable bacillus may fail to agglutinate at all (at 1 in 25) with a 

 serum that agglutinates the culture from which it was derived up to 1 in 

 1000 or more. It may also entirely fail to absorb from the serum any appre- 

 ciable quantity of the agglutinins specific to that culture. 



4. These results appear to necessitate a considerable modification of current 

 theories regarding the value of absorption tests as a means of determining 

 bacterial affinities, but may help to throw some light on the difficult problem 

 of " serological strains." They show how necessary it is to reserve one's 

 judgment, where conclusions are drawn regarding true differences of bacterial 

 type, in cases where the differentiation rests solely on agglutination and 

 absorption tests ; since differences of such remarkable degree are shown to 

 exist between different individuals among the population of a single culture. 



I desire to express my indebtedness to Dr. A. D. Gardner, who kindly 

 made independent readings of a number of my agglutination tests, and to 

 Miss Edith F. Stubington for frequent and willing help in many of the more 

 laborious experiments. 



EEFERENCES. 



(1) Walker, E. W. Ainley, ' Journ. of Pathology and Bacteriology,' vol. 7, p. 250 (1901 



(2) Gardner, A. D., 'The Lancet,' vol. 2, p. 494 (1920). 



(3) Walker, E. W. Ainley, 'Journ. of Hygiene,' vol. 17, p. 380 (1918). 



(4) Gardner, A. D., and Walker, E. W. Ainley, ' Journ. of Hygiene,' 1921 (in the press). 



(5) Arkwright, J. A., ' Journ. of Pathology and Bacteriology,' vol. 24, p. 36 (1921). 



(6) Vines, H. W. G, ' Journ. of Pathology and Bacteriology,' vol. 22, p. 197 (1918). 



(7) Walker, E. W. Ainley, ' Journ. of Pathology and Bacteriology,' vol. 8, p. 34 (1902). 



