26 



All of the milk retailed at 6 cents a quart, quite often in glass 

 bottles if desired. In so far as the food value of the milk was con- 

 cerned, it is certain that the consumer was paying a very moderate 

 price for this article of food. 



J. Bacteriological Analysis of the Milk. 



'I'he most common forms of bacteria usually 



Common forms found in milk may be classified and briefly 



of Bacteria described as follows : 



in Milk, /. Acid Inxcteria. {\\. acidi lactici. I pnd II, 



and IJ. lactis aerogenes). 'J'he name was 



given because they produce lactic acid from the sugar of the milk. 



The common forms of lactic acid organisms are comparatively few 



in fresh milk — usually below 30 per cent of the the total number 



of bacteria — but develop with great rapidity at ordinary temperature 



(70° Fahr.) and as a rule overcome the other forms. Ordinarily 



most of the bacteria in old milk consist of the harmless lactic acid 



organisms. 



II. Kapid and Slow Liquejiers. A number of different species 

 compose this group which is so named because of its ability to liquefy 

 gelatin. Rapid liquefiers are relatively few in number in fresh clean 

 milk, and are eventually overcome by the lactic acid bacteria. They 

 produce putrefaction by attacking the nitrogenous matter of the milk, 

 and their presence in large numbers probably renders the milk un- 

 wholesome. 



vSlow liquefiers produce enzymes and most of them cause putrefac- 

 tion. They are not found in the milk as it comes from the udder, nor 

 are they found in well cleaned milk pails, and their presence in milk 

 in considerable numbers is an indication of dirty cows or stable. 

 Such milk must be regarded as unsanitary. 



III. All Others. Under this grouping is included a considerable 

 variety of species, such as the so-called neutrals, those producing 

 yellow or red brown colonies, and those peculiar to certain samples 

 of milk, and not found in other samples.' 



'Pathogenic bacteria, wliicli cause such diseases as tuberculosis, diphtheria and typhoid 

 fever also gain access to milk, but are not considered in this connection. 



