VIII. B, 6 Barber: Dysentery Bacilli 547 



type. The mixed tubes were done in triplicate, 3 tubes to each 

 kind of broth. The unmixed red and blue strains retained their 

 characteristics through 15 daily transfers in each kind of broth. 

 Of the 9 mixed tubes, all showed mixtures of red and blue 

 strains at the end of the fifteenth transfer, except 2, 1 maltose 

 and 1 mannite, which became distinctly acid at the fifth transfer. 



These three series indicate that, whether in plain, mannite, or 

 maltose broth, the characteristics of the two types remain 

 constant if daily transfers are made. If the two strains be 

 equally mixed in the same tube, sometimes the red and sometimes 

 the blue gets the upper hand, but there is a tendency for the 

 red strain to predominate. 



Most authors have found that a new fermentative character 

 is acquired only in contact with the corresponding sugar and 

 that older cultures in the sugar have given more pronounced 

 variation than fresh cultures after repeated transfers at short 

 periods. The older cultures afford the time necessary for the 

 exhaustion of the preferred sources of nutrition, after which the 

 bacteria may acquire the power of attacking the unusual food. 

 Baerthlein -^ found that a paratyphoid-like race of bacilli, grown 

 on lactose-containing media, kept its characteristics when trans- 

 ferred every twenty hours, but, transferred at somewhat longer 

 intervals, it acquired the power of acidifying lactose. Josef 

 Klein, ^^ working with Bacterium coli midabile, found that many 

 generations in a lactose-free medium did not produce the lactose 

 ferment, while relatively few generations in a medium poorly 

 supplied with nourishment, but containing lactose, brought about 

 lactose fermentation. Mere contact with lactose at a tem- 

 perature too low for active multiplication failed to develop the 

 lactose ferment. Twort " succeeded in developing the power of 

 fermenting dulcite and lactose in a strain of typhoid by fort- 

 nightly transfers in a medium containing these substances. 

 Hiss ^^ found that a strain of dysentery, type Y, cultivated for 

 some time in maltose, had acquired the power of fermenting 

 that sugar. On the other hand, Lentz -^ describes a Flexner 

 strain which, after seven years' cultivation, lost the power to 

 ferment maltose, while retaining its specific agglutinating power. 



''Centralbl. f. Bakt. etc., Orig. (1912), 66, 21. 

 -' Zeitschr. f. Hyg. u. Infectionskrankh. (1912), 73, 87. 

 "Proc. Roy. Soc. London (1907),. B, 79, 329. 

 '-'' Journ. Med. Research (1904), 13, 36. 



* Kolle und Wasserman, Habk. Handbuch der pathogenen Mikroorgan- 

 ismen. Gustav Fischer, Jena (1909), Erganz-Bd. 2, 407. 



