51 



Clemesha (1912) has made numerous observations on the relative 

 incidence of glucose and lactose fermenting bacilli in waters of India 

 subjected to various periods of storage, exposure to sunlight, and filtration. 

 In Table XXIII. taken from his book on the bacteriology of Surface Waters 

 in the Tropics are shown the effects of treatment and the influence of self 

 purification on the relative incidence of glucose fermenting bacilli which 

 are not lactose fr actors. 



The increased incidence of glucose positive-lactose negative organisms 

 in waters during dry weather is particularly striking. Thus during the 

 rainy month of October 40 to 50 percent of the strains studied were of this 

 type, the number gradually increasing as the river cleared and the forces 

 of natural purification (sedimentation, sunlight, etc.) manifested them- 

 selves until in February, 93.7 to 98.2 percent of the glucose fermenting 

 strains were non-lactose fractors. The glucose broth presumptive test is 

 therefore particularly unreliable as an index of the colon group when 

 dealing with treated and stored waters. 



Clemesha attributes the marked increase of glucose -(-, lactose , 

 bacilli in India stored waters to the presence of an organism which he 

 designates Bacillus P. This bacillus is widely distributed in nature, ex- 

 tremely resistant and capable of multiplying in water. 



The important characteristics of the organism are given below: 



Morphology, etc. Gram positive, motile bacillus. 



Litmus Milk. Slight acidity on top (occasionally). No coagulation. 



Indol. Negative. 



Gelatin. Not liquefied in ten days. 



Fermentation. Glucose acid and gas. 

 Sucrose acid and gas. 

 Lactose. Faint trace of acid on long cultivation in 



laboratory. 

 Dulcitol 



Mannitol 

 Adonitol 



Neither acid nor gas 



Inulin 



Voges Proskauer Reaction. Strongly positive. 

 Bacillus P. of Clemesha resembles the B. proteus but differs from it 

 in being Gram -|- an d giving a positive Voges Proskauer reaction. 



Not only is gas production in glucose broth a poor index of probable 

 presence of Bact. coli but the organism may be present even in the absence 

 of gas formation, particularly if the water has a high bacterial count or 

 contains streptococci. It is not infrequently observed with this medium 

 that small samples of water (1 c. c. or 0.1 c. c.) may be positive whereas 

 larger portions (10 c. c.) may be negative. Upon considering that there 

 are numerous organisms capable of attacking glucose with acid produc- 

 tion, this choking off of the colon bacilli may be readily explained by the 

 inhibiting action of the acids formed. 



