DIRTY MILK 



69 



There are good bacteria and bad bacteria. Fortunately 

 all the bacteria in milk are by no means harmful. Some of 

 them may even be beneficial under certain circumstances. 

 So far as mere numbers are concerned they need not greatly 

 alarm us, for we know that disease is due to agencies and 

 conditions other than merely the presence of enormous 

 numbers of bacteria. By universal consent, however, milk 

 containing excessive numbers of bacteria is not a suitable 

 food. The tender mucous membrane of infants is very sus- 

 ceptible to bacteria and their products, and a certain pro- 

 portion of the summer complaints of infants may be traced 

 directly or indirectly to the use of bacteria-laden milk. 

 As we grow older, it seems that the gastro-intestinal mu- 

 cous membrane becomes comparatively immune or hard- 

 ened, so that it is able to resist bacterial action which would 

 be injurious or fatal to the tender infant. 



If milk were a transparent liquid, the enormous growth 

 of bacteria often found in market milk would be plainly 

 visible to the naked eye. A similar amount of bacterial 

 growth in broth, gelatine, beer, jelly, or other clear sub- 

 stance would render such food unsightly, and it would 

 generally be regarded as unfit for use on account of the 

 evidence of bacterial growth, if not on account of the evi- 

 dence of actual fermentative and putrefactive changes. 



The number of bacteria in milk is not so important from 



