134 APPLIED BACTERIOLOGY FOR NURSES 



serves as a conductor of heat. The filled rack is im- 

 mersed into the boiling water in the pail, the pail is 

 removed from the stove, and the cover replaced. Within 

 ten minutes the temperature of both water and milk 

 reaches 160 F. and remains at that level for about 

 twenty minutes. Then the bottles are removed and 

 rapidly cooled in the water-bath, or, better, the hot 

 water in the pasteurizer is replaced by cold, which is run 

 in by means of a rubber tube attached to the kitchen 

 faucet. The milk is then stored on ice. 



Milk as a Carrier of Disease. Besides the above bac- 

 teria, which are inevitable inhabitants of all market milk, 

 and which vary in the different grades of milk in number 

 only, other and much more serious contaminations may 

 occasionally be found. Of those derived from the cow 

 the most frequent are streptococci from a suppurative 

 mastitis, and the tubercle bacilli from udder tuberculosis 

 or tuberculous lesions elsewhere. It has been demon- 

 strated that while the tubercle bacillus found in cows is 

 not of the same variety as that which produces pulmonary 

 tuberculosis in adults, it is nevertheless able to set up even 

 fatal tuberculous processes in small children and infants. 



Typhoid fever is not infrequently spread by means, of 

 milk; the bacillus is introduced into the milk directly, 

 through uncleanly habits of the milkers, among whom 

 there may be a so-called "carrier/' that is, an apparently 

 perfectly healthy individual who harbors in his intestines 

 virulent typhoid bacilli, or, indirectly, by contaminated 

 water which has been used to wash utensils, etc. 



Asiatic cholera, dysentery, and similar diseases may 

 be spread in the same manner, but are probably only 

 infrequently disseminated in this way. Epidemics of 



