SANITARY MILK PRODUCTION 163 



growing plants or are derived from the soil or else from human sources 

 in the course of garnering or manufacturing. Organisms of the B. 

 subtilis group, of the butyric acid group, and of the B. coli-Bact. aerogenes 

 group, all have been found abundantly in feeds. It has been noted that 

 condensed milk is sometimes spoiled by gassy fermentations produced 

 by spore-bearing organisms and that this trouble is most likely to occur 

 in the autumn when crops are being put into the barn and the stable air 

 is filled with dust. 



Contamination from Bedding. Bedding is the source of many kinds 

 of bacteria and of moulds, among the former, those of the B. coli-Bact. 

 lactis aerogenes, the B. subtilis and the butyric acid groups may be men- 

 tioned. Clean bedding such as shavings, sawdust, peat moss, cocoa 

 shells, etc., gives little trouble but dusty, smutty or mouldy bedding and 

 a litter of fallen leaves, horse manure or of sand all are likely to produce 

 ill effects on the milk. One of the worst litters from the point of view of 

 bacterial contamination that the author ever had to deal with was a 

 coarse hay that was cut on a meadow subject to periodical overflow by 

 a muddy river. Brainerd, at the Virginia Agricultural Experiment Sta- 

 tion, made a short series of experiments in the Station stable to determine 

 the source of bacteria in the milk produced there. Among other things 

 he found that when bright clean straw was used as a litter the bacterial 

 content of the milk could be decidedly reduced by moistening the straw 

 before milking, and that with sawdust for a litter as good bacterial results 

 were obtained as with moistened straw. 



Contamination from Dairy Utensils. Dairy utensils have been 

 pointed out by several bacteriologists as a fertile and serious source of 

 milk contamination. The trouble corner about in this way: a little milk 

 containing bacteria or their spores is left adherent to the vessels in the 

 form of inconspicuous drops, or an in visible 'film or ever so slightly milky 

 water that condenses at the time of scalding or steaming. These microbes 

 establish themselves on the utensils and may multiply on them; in either 

 case, they germinate in the milk that is next put in. Hasty, careless 

 cleaning is partly to blame for this sort of pollution but it is also partly 

 due to faulty construction of the utensils, to washing being done in the 

 wrong way and to scalding or sterilizing being neglected. 



All utensils should be made with as few seams as possible and the 

 necessary ones should be flushed with solder so that there will be no 

 crevices in which milk can accumulate and be decomposed by bacteria. 

 So far as practicable, utensils that are inconvenient to clean should be 

 discarded; certain covered milk pails and cream separators are of this 

 sort. 



New tinware is easily kept clean but that which is rusted and that 

 which by rough usage has had the tin plate knocked off cannot be cleaned 

 so that there will not be large numbers of germs in the spots and crannies 



