266 MILK AND ITS HYGIENIC RELATIONS 



ducing the disease will be passed out into the milk, which will be 

 contaminated at its site of production. This subject has already 

 been dealt with in Chap. XV. 



It has also been noted in Chap. VII that streptococci, and hence 

 presumably other organisms, may gain entrance to the teats from 

 the outside of the udder and teats. 



The first jets of milk which leave the udder on milking are 

 known to contain a larger number of bacteria than the later portions, 

 and it is usual in producing milk of a high quality to reject the 

 first portion of milk. 



Further, the cows, unless cleaned, usually have their hind- 

 quarters contaminated by faeces and urine. Faecal matter is replete 

 with organisms, of which the most characteristic and the best known 

 are those of the coli group. The presence of Bacillus coli is usually 

 regarded as diagnostic of faecal contamination. When present in 

 milk it is probable that its main source of origin is from the faeces 

 of the cow. The faeces are allowed to dry on the hindquarters 

 of the animal and tend in the process of friction of the milker 

 against the cow to fall or be wafted by air currents into the milking 

 pail. The greater part of the dirt, i.e. sediment, which is found in 

 milk is well known to be mainly composed of faecal material. A 

 small amount of such material in the milk provides a rich supply 

 of coli organisms. 1 



It is not necessary to consider at length the literature upon this 

 subject, but it may be mentioned in passing that Hewlett and 

 Barton, examining milk as it came into London from a very large 

 number of English counties,found that in 46 per cent, of the samples, 

 Bacillus coli was present in i c.c. of milk. It is probable that 

 had larger quantities of milk been taken, the percentage would have 

 been still higher. 



Other organisms will be attached to the hair of the cow and, 

 together with the hairs rubbed off in the process of milking, will 

 fall into the milk. On farms where milk with a low bacterial count 

 is produced, it is not unusual for the cows' udders to be clipped in 

 order to remove the. main growth of hair. Such clipping is probably 

 especially valuable in certain cases where the hairs grow almost 

 on to the teats and will be rubbed in the process of milking. Where 

 the milker leans his head against the side of the cow, hair from the 

 cow's flanks will also fall probaoly into the milk. 



2. From the Milker. The milker's hands are a potent source 

 of origin for bacteria in milk. In the course of milking any dirt 

 which is on the hands will gradually be rubbed off and find its 

 way into the milk. A practice exists among dirty milkers of milking 

 with their hands moistened by means of their own saliva. This 

 revolting practice, which is known as ' wet ' milking, clearly adds 

 to the bacterial contamination of the milk. In the first place 



1 The remarks of the Royal Commission on tuberculosis, quoted on p. 253, 

 may also be referred to. 



