BIO-CHEMICAL CHARACTERISTICS OF BACILLI. 87 



Technique. — For all "sugar" tests 1% litmus peptone 

 water containing the various sugars \°/ strength was used, 

 except in the case of glucose, mannit, lactose and cane- 

 sugar, where 1% strength was substituted. The solutions 

 were put up in test tubes with Durham's gas collecting 

 tubes. All sugars are from Merck, except saccharose, 

 which is ordinary brewers' crystals. 



The results following are made up from the notes of 

 nearly a year's work, during which time the majority of 

 the tests have been applied at least twice. 



In Table I. are displayed the bio-chemical reactions of 

 thirteen cultures from European laboratories labelled para- 

 typhosus or paracolon. This table incidentally shows the 

 media used and the general method adopted. 



The reactions of the various " sugar " media are identical 

 in quality, though variable to some extent in quantity. 

 Thus there is some variation in the time taken to ferment 

 dulcit, some cultures giving acid and gas on this sugar in 

 twenty-four hours, others taking several days. But as 

 considerable variations occurred in individual tests of cer- 

 tain organisms, it was not thought advantageous to rely 

 much on this characteristic. All, however, are able to 

 ferment dulcit within four days. 



A similar but less marked irregularity is found with 

 maltose, galactose and arabinose. As regards morphology, 

 motility, and growth on agar, I do not wish to dwell, except 

 to say that I have found no useful distinguishing properties 

 by these tests. 



Litmus milk is usually regarded as a valuable means of 

 separating two types of b. paratyphosus, A and B. Type 

 A being said to give slight permanent acidity, Type B, 

 " Cameleonage" or acid followed by alkaline reaction ; but 

 it will be seen that there are several variations in the type 



