1912.] 



On the Variability of Streptococci. 



40& 



In all the tables the sign 4- indicates the production of an acid reaction in 

 the sugar medium, or the reduction of neutral red, or the production of a 

 clot in milk where the property of clotting milk is under examination. The 

 sign indicates that the change in question did not occur within the limits of 

 time prescribed for Gordon's tests. 



Table II contains the results obtained by testing the streptococcus A in 

 its original form, and after each successive passage through the mouse. 

 There are eight changes of individual reactions. All six series of reactions 

 are different, and each of them is different from the reactions shown in 

 Table I from the cultures grown in bouillon, gelatin, and milk. 



Table II. — Showing the Eeactions of Streptococcus A when first Isolated and 

 after each of Five Passages through the Mouse. 





Milk. 









































Streptococcus A. 







1 



1 



2 











ll 







Clot 



J? 



1 



02 



§ 









1 









+ 







+ 



+ 



+ 



+ 















+ 



+ 







+ 



+ 



+ 



+ 









1 





+ 









+ 









+ 







°o 



3 





+ 



+ 



° 



+ 











+ 





2 





+ 



+ 





+ 



+ 



+ 











1 



„ five „ 



+ 



•+ 















+ 







1 























Thus it appears that, starting from a single freshly isolated streptococcus of 

 undoubted purity, no less * than ten distinct varieties, or variants, were 

 obtained. The only instances of identical reactions which occurred were 

 those exhibited by the variants obtained after two months' growth in 

 bouillon and two months in milk, and the variants got by one month's 

 growth in bouillon and two months' growth in gelatin. 



In Table III are given the reactions of the streptococci L, P, G-, M, V, E, in 

 January, 1912, along with the results which they had yielded previously from 

 stock agar cultures in 1908 and 1910, as shown in my previous papers. 

 G is the only streptococcus which, in 1912, exhibits the same series of 

 reactions as in 1910. Numerous changes are seen in the reactions of the 

 streptococci. Streptococci S and H of my previous list could not be 

 re-examined as they had unfortunately been allowed to die out. Streptococcus 

 E was one originally isolated from horse-dung, all the others were of human 

 derivation. 



