128 The Philippine Journal of Science 1913 



Suffice it to say that some of them will stand almost any kind of 

 treatment without change, while some specimens of maltose sent 

 out by our best manufacturers are already partly inverted when 

 the packages are opened. 



My plan was to study the reactions of a large number of 

 strains of the dysentery bacillus, by running along with these 

 a considerable number of other organisms whose exact identity 

 was known. The same set of organisms was always planted 

 along with the dysenteries into any given lot of medium. In 

 this way a score of trials of the bacterial action on the several 

 carbohydrates have been made during the past four months. 

 Sixteen strains of Bacillus dijsenteriss have thus been tried a 

 number of times against 16 other organisms under exactly sim- 

 ilar conditions. Some of the dysentery strains were laboratory 

 cultures for which I am indebted partly to Maj. P. M. Ashburn 

 of the Tropical Board, and partly to Dr. M. A. Barber of the 

 Bureau of Science. Other strains were isolated from the dysen- 

 teric stools of patients. The advantages of this method of 

 multiple bacterial cross control will upon reflection be evident. 

 If, for instance, as was frequently noted to be true, the 8 or 

 10 strains of Shiga's bacillus in the series were found to ferment 

 maltose when they had refused to ferment mannite, it was hardly 

 likely (with tlie precautions taken to guard against contamina- 

 tion) that all of these could be explained on the basis of mixed 

 cultures. And, if all the other bacteria in the series acted in 

 this set as they should have acted upon glucose, it is pretty 

 evident that the fault lay in the maltose. If, however, an 

 isolated tube in the series gave some unexpected result, it in- 

 dicated an impure culture. That culture was then plated and 

 reidentified. If the lactose had been hydrolysed in the manipu- 

 lation, all the bacteria in the series would act not as upon 

 lactose, but as they should act upon dextrose and galactose. If 

 the sucrose has not remained intact, but is inverted, the baterial 

 series will act, not as upon sucrose, but as upon dextrose and 

 levulose. In working with the carbohydrates in this way it is 

 soon evident that if we start with a chemically pure carbo- 

 hydrate (which alone should be used in bacteriology) and do 

 not add to it acids and alkalies, it will stand one decisive auto- 

 claving better than it will heating for three successive days in 

 the Arnold sterilizer. It is not requiring too much of any sub- 

 stance used in bacteriological work that it be able to stand the 

 manipulations necessary to get it sterile, and, if it will not do 

 this without change, it should be rejected. It was very soon 



