244 CLEAN MILK 



given milk supply using identical technique and each securing the* 

 same set of counts from the dilutions made, but differing as. 

 to calculation of count, they might report from such figures as the 

 above, no less than seven different results, all justified by existing- 

 (but erroneous) methods of calculation. Owing to the fact that 

 it is not usually the custom to make more than two or three dilu- 

 tions, and these not necessarily the same, the actual number of pos- 

 sible reports from the same milk if badly contaminated is about 

 fifteen, ranging from 25,000 to 2,000,000. 



If different techniques are used, especially as regards medium, 

 temperature and time of incubation, results differing from 50% to 

 200% may be obtained from the same sample, even using the same 

 methods of calculation. Hence the absolutely essential need for 

 uniformity of technique and uniformity of calculation. Neither 

 one alone will give figures of any moment zuhatever. 



Interpretation of Count. — Attention to condition of cow, clean- 

 liness, cold, and quickness in transportation, as described elsewhere 

 in this book, will alone secure low count milk. Failure in any 

 one of these essentials is faithfully recorded by the bacterial count. 

 Indeed, the bacteria in milk may be regarded, from the standpoint . 

 of the sanitary milk inspector, as a tell-tale or automatic register,, 

 of the treatment the sample tested has received in these regards. 

 Neglect of any necessary precaution is written down by these faith- 

 ful " recording angels " for the bacteriologist to read. 



The simple count, taken alone, while it gives the sum total 

 effect of whatever mistreatment the milk may have received, does 

 not indicate what the mistreatment was, i. c, whether it lay in 

 neglect of the cow, admission of dirt, high temperature, or lapse 

 of time. If the differentiation of these is desired, it may be 

 achieved only by learning the history of the milk, and thus deter- 

 mining which factor or factors suffered neglect. If the history of 

 the milk shows delay in transportation, especially with lack of cool- 



