58 VARIATIONS IN FERMENTING POWER [ch. v 



of three intra-peritoneal passages through the guineapig. 

 Another similar strain from ascitic fluid after several passages 

 was still unable to produce gas from glucose or dextrose. 



VII. Variation in th^ fermenting power of organisms 

 may arise during the course of a disease. 



Connal (1910) has shown that in the later, chronic, stages 

 of cerebrospinal fever the meningococcus isolated from the 

 spinal fluid has lost its power to ferment dextrose. 



Adami, Abbott and Nicholson (1899) in describing diplo- 

 coccic forms of B. coli, isolated from the ascitic fluid in 

 cases of hepatic cirrhosis, mentions that they had lost the 

 power of fermenting glucose and lactose broths. 



VIII. The power to ferment a "sugar" may he acquired 

 by bacteria after prolonged growth in a medium containing 

 that sugar. 



Hiss (1904) has described a bacillus of the dysentery group 

 which acquired the power to ferment maltose after being 

 grown for some time in a maltose medium. 



Twort (1907) found that dysentery bacilli (both the 

 "Flexner" and the "Shiga" type) which did not normally 

 ferment saccharose, did so after cultivation in a medium 

 containing this ingredient, and by similar means the true 

 " Shiga Kruse " organism was induced to ferment lactose. 



In the same way he found that members of the paratyphoid 

 group, after prolonged cultivation on a saccharose medium, 

 all acquired the power to ferment it, while a strain of B. 

 typhosus acquired the power to ferment lactose, but only 

 after two years' "training." The same organism could be 

 made to ferment dulcite in a very shorter period, 2 or 3 weeks 

 being suflBcient. 



Penfold (1910) trained B. typhosus to ferment dulcite in 

 a period of 10 days, arabinose in 2 or 3 months and isodulcite 

 after varying intervals. He failed however to develop new 

 fermenting powers on the part of the same organism towards 

 lactose after a 15 months' trial, or towards saccharose and 

 other substances after 9 months. 



