200 BACTERIA 



the addition of typhoid-infected water, either by way of 

 adulteration or in the process of washing out the milk-cans. 

 Cases have, however, been recorded in which there has been 

 direct transmission to the milk from a person convalescing 

 from the disease, and also indirect transmission by a milker 

 serving also in the capacity of nurse to a patient in his own 

 family. 



Though the typhoid bacillus appears not to have the 

 power of multiplying in milk, it has the faculty of existing 

 and thriving in milk, even when it has curdled or soured, 

 for a considerable time, and may thus infect milk products 

 like butter and cheese. But infection by milk products may 

 be eliminated as of too rare occurrence to deserve attention. 

 The bacillus does not coagulate the milk like its ally the 

 Bacillus coli communis, which is a much more frequent and 

 less injurious inhabitant of milk. 



Cholera. The cholera bacillus, as we have already pointed 

 out, is unable to live in an acid medium. Hence its life in 

 milk is a limited one, and generally depends on some alka- 

 line change in the milk. Heim found that cholera bacilli 

 would live in raw milk from one to four days, depending upon 

 the temperature. D. D. Cunningham, from the results of a 

 large number of investigations in India, concludes that the 

 rapidly developing acid fermentations normally or usually 

 setting in, connected with the rapid multiplication of other 

 common bacteria and moulds, tend to arrest the multiplica- 

 tion of cholera bacilli, and eventually to destroy their vital- 

 ity. Boiling milk appears, on the contrary, to increase the 

 suitability of milk as a nidus for cholera bacilli, partly by its 

 germicidal effect upon the acid-producing microbes, and 

 partly because it removes from the milk the enormous num- 

 bers of common bacteria, which in raw milk cause such 

 keen competition that the cholera bacillus finds existence 

 impossible. 



Professor W. J. Simpson, lately the Medical Officer of 



