QUANTITATIVE BACTERIAL ANALYSIS 245 



iing in transit, a dirty, dusty barn, utensils, or animal, or a gargety 

 •cow, the count, may be attributed to these. 



Confirmation of these may be obtained in two directions — the 

 height of the count and the character of the bacteria present, the. 

 latter involving considerable additional bacteriological work for its 

 -final determination. This outline cannot be considered wholly final, 

 but as yielding strong indications, which should be confirmed by 

 •actual investigation. 



A high count, almost wholly consisting of lactic acid bacilli = 

 probability of slow transit, at a temperature of 6o° — 8o u . (The 

 acidity of such a sample would be high.) 



A high count, with a variety of bacteria, lactic acid bacilli not 

 prominent = probability of slow transit at low temperatures, 30 ta 

 50 . (The acidity of the sample would be moderate.) 



A high count, showing many spore-forming bacteria, without 

 great acidity=probability of pasteurization, followed by too long 

 keeping at too high a temperature. 



A high count, showing a very large variety of forms, especially 

 fluorescent and chromogenic forms, suggests extensive contamina-^ 

 tion from dust, etc., or possibly from watering. If the milk is fresh 

 and not very acid, the " dirt " origin of the bacteria is largely 

 -confirmed. 



A high count, consisting chiefly of streptococcus colonies, 

 points to a gargety condition in the cow. 



A low plate count, since it gives the living bacteria, combined 

 with a high direct count by Slack's method, since this gives dead 

 as well as living bacteria, suggests recent pasteurization of a high 

 count milk. 



The propositions converse to the above will not always hold 

 true, however, and many combinations arise, the interpretation of 

 which cannot be made easily, since frequently many of the factors 

 .given operate at one time, but in different proportions in different 

 cases. Only the simpler basic combinations are stated here. The 



