A STUDY OF SPONTANEOUS AGGLUTINATION 77 



originalh' of a sjiontancou-sly agglutinating variety, showed no 

 change after one hundred days. Eighteen strains of Bad. para- 

 typhosum A showed changes in from ten to eighty-five days, 

 two strains of an agglutinating type, showed no change until 

 after one hundred days. Nineteen strains of Bad. paratyphosum 

 B. showed changes in from fifteen to one hundred days, while 

 two strains of spontaneously agglutinating type did not change 

 even in one hundred days. All strains of Bad. coli showed a 

 change in from ten to thirty days. Bad. enteritidis was examined 

 after GO days growth, and all 8 strains showed a change. With 

 the Bad. dysenteriae group two strains showed changes in thirty- 

 five to forty days, while two strains showed no change after 

 sixty days. 



The period at which the change in colony occurs depends 

 upon the strains; some strains always change within a short 

 time and others only after many days. 



ISOLATION OF TYPES OF COLONY FROM STOCK CULTURES (TABLE 3) 



In our first work with stock cultures three types were found. 

 These were, pure colonies not showing spontaneous agglutina- 

 tion, pure colonies showing spontaneous agglutination and 

 mixed colonies showing the presence of both types. 



In a study of the colon-typhoid group of bacilli from agar 

 stab cultures which had ordinarily been sub-cultured at inter- 

 vals of two or three months, there were found many cultures 

 producing colonies of only one kind, namely those which agglu- 

 tinated spontaneously; other cultures yielded colonies of bacilli 

 all of which failed to agglutinate spontaneously. 



In the present work extending over a period of a year, it was 

 found that each pure type after frequent transplantation tended 

 to change into both types; of 29 strains of Bad. typhosum show- 

 ing pure colonies of the spontaneous agglutinating type only 3 

 strains remained unchanged. Of 4 originally pure strains of 

 Bad. coli used only 2 adhered to the original type. Bad. para- 

 typhosum A (19 strains) Bad. enteritidis (9 strains) and Bad. 

 dysenteriae (3 strains) showed both types of colonies. Bad. 

 paratyphosum B (21 strains) showed both types of colonies, but 



