276 



MILK AND ITS HYGIENIC RELATIONS 



are kept back, but these gross particles should not be present. 

 They are usually portions of dried faecal material which have become 

 detached from the cow, and should be absent. 



Ulax filter, (i ) Shows a section of the filter} The milk is poured on 

 to the top part, and is filtered through a layer of woolly substance 

 (4), which is held in position between wire-discs (3), and the 

 piece (2), which is secured by a metal spring: 



Savage gives data upon the bacterial content of milk which 

 had been filtered and of similar samples which were not filtered. 

 He quotes two sets of experiments, one set in which the Ulax 

 filter was used (see figure), and another in which a different 

 strainer was used. 



The milk is said to have been collected in the ordinary way 



