20 MILK AND THE PUBLIC HEALTH chap. 



The udder and teats have only to he washed in clean water, 

 and the water looked at, to demonstrate their filthy condition. 

 Such manurial matter is, of course, loaded with bacteria. As 

 an illustration of the enormous number of bacteria in manure, 

 the following figures obtained by Orr ^ may be quoted : 



It is, of course, chiefly the old dried manure which gets 

 into the milk. 



The kinds of organisms present are very numerous. That 

 bacteria of the streptococcus and coli classes are abundant, is 

 shown by the following figures obtained by the writer ^ for 

 quite fresh excreta: 



Ap'proximctte Nunibei- per gramme of Excreta. 



During milking an appreciable portion of manure drops 

 into the milking -pail. This contamination is greater in 

 winter than in summer when the cows are generally out of 

 the sheds for most of the day and night, and are consequently 

 cleaner. Some experiments of Orr (loc. cit.) illustrate this. 

 A number of agar-plates were held under tlie udder during 

 the process of milking for two minutes each, and after exposure 

 were incubated (4 days at 20° C). From the respective areas 

 of the plates and the ordinary milk-]iail, it would be possible 

 to calculate the number of organisms falling into the milk- 



^ Report on Milk Contamination, 1908, pp. 19-20. 

 - Bacteriological Ej:aiiunation of Water Supplies, 1906, p. 35. 



