DESTRUCTION OF TYPHOID AND COLON BACILLUS. 457 



to tlie iiitiuence of tlie common water bacteria or of their products 

 ii])Oii the vitalit}^ of the typhoid bacilhis. 



A research rehitiiig to the iuiiuence of the common water bacteria or 

 of their products upon the vitality of the typhoid and colon bacilli was 

 then undertaken. Three series of experiments were made, the lirst to 

 ascertain whether the typhoid and colon bacilli would grow on media 

 containing the products of growth of the water bacteria; the second to 

 verify tlie first, to meet any objection that might be raised as to the 

 sterilizatiou by heat of the medium in which the water organisms had 

 grown, as the opinion has been advanced that some products of the 

 activity of bacteria are either volatile or rendered inert by high tem- 

 peratures. The third experiment was made to find whether the two 

 organisms would grow with the water bacteria. These series of experi- 

 ments were conducted in the following manner: 



(1) Forty-four varieties of bacteria obtained from the water of the 

 Schuylkill lliver were used in the first exi)eriiiieiit. A pure culture of 

 each organism was inoculated upon slanted tubes of agar-agar and 

 allowed to attain a luxuriant growth. The tubes were then thoroughly 

 sterilized in the steam sterilizer, the reaction was taken, and the 

 medium was again slanted. A set of these tubes was then inoculated 

 with the bacillus typhi abdomiiialis, and a second set with the bacillus 

 coli communis. As a result of this research it was found that the 

 typhoid and colon bacilli grew upon these tubes in every instance, the 

 growths varying in thriftiness from luxuriant ones on some tubes to 

 transparent films on others. 



(2) In the second series which w^ere made to verify the first^ — that is, 

 to find whether the products of the activity of water bacteria in the 

 medium used would retard or prevent the growth of the tyi)hoid and 

 colon bacilli — the water bacteria were inoculated into Erlenmeyer fiasks 

 of bouillon, each containing 70 c. c, and placed in the incubator. After 

 being incubated from fifteen to twenty days the cultures were filtered 

 through i)orcelain, the reaction was taken, and the filtrate was run into 

 sterilized tubes. Two sets were made as before and inoculated with 

 the typhoid and the colon bacilli, respectively. These tubes were then 

 incubated for twenty-four hours, and from them gelatin tubes were 

 inoculated and poured into Petri plates. In each of these inoculated 

 filtrates the two organisms grew in a characteristic manner and multi- 

 plied for at least four days. 



(3) In the third experiment thirty-nine varieties of the water bacteria 

 were inoculated into tubes, each containing 10 c. c, of sterilized tap 

 water and o drops of sterilized bouillon. Two sets of tubes were made 

 as before, and each set inoculated with one of the organisms which was 

 being tested, and each tube contained a different variety of water bac- 

 teria. From these tubes gelatin j)lates were made each day for more 

 than twelve days. Both bacilli gave characteristic colonies with each of 

 the water organisms except tw^o, which had apparently an antagonistic 



