TYPHOID 173 



as to their vitality, and as to the retention of their dif- 

 ferential characters in waters of different composition and 

 quality. He also took the two organisms derived from 

 sources outside the human body (namely, from excre- 

 mentally polluted water-supplies). These were passed from 

 subculture to subculture, and were passed from peri- 

 toneum to peritoneum in separate series of guinea-pigs, 

 they being cultured through no less than thirty genera- 

 tions. Whatever the source of the bacilli, and whatever 

 the experimental conditions in the laboratory or the animal 

 body to which they were exposed, each organism retained 

 unimpaired its differential characters, and at no time 

 showed the least tendency to depart from the characters 

 generally accepted as being exhibited by these organisms. 

 Incidentally during the course of these experiments, it 

 appeared that the persistence in a water medium of both 

 the typhoid bacillus and of the Bacillus coli is largely 

 governed by the chemical constitution of the water. 



Conveyance by Milk. — It is believed by some observers 

 that cows may suffer from enteric fever and transmit it in 

 their milk. Whether this is so or not, it is certain that 

 epidemics may and do arise from the washing out of the 

 churns with polluted water, or when the milk is adulterated 

 with polluted water. The bacillus of typhoid multiplies in 

 milk enormously faster than in water, and a vessel left 

 damp with moisture containing only a few organisms 

 would be capable of infecting its entire contents of milk 

 in a few hours. It would be to the public interest if the 

 adulteration of milk by the addition of water was made 

 a more serious offence than it is at present, seeing what 

 far-reaching consequences it may have. The establishment 

 of creameries in many parts of the country is likely to 

 prove an additional danger in the dissemination of milk- 

 borne disease. At these creameries the milk of a con- 



