142 BACTERIA IN DAILY LIFE 



be discarded for dietetic purposes. Professor 

 Ostertag, at the request of the German Govern- 

 ment, has carried out a most elaborate and very 

 extensive series of investigations to determine 

 the question as to whether such milk is danger- 

 ous to health. I cannot do better than quote 

 the conclusions appended to the original memoir, 

 in which Professor Ostertag expresses himself as 

 follows : " The milk of cows which only react to 

 tuberculin does not contain tubercle bacilli ; calves 

 and pigs can be fed during weeks and months 

 with milk derived from such cows without con- 

 tracting tuberculosis." 



A very important rider, however, is added, in 

 which it is pointed out that inasmuch as no doubt 

 exists as to the highly infectious character of the 

 milk derived from cows the udders of which are 

 tuberculous^ and from animals in which the disease 

 is clinically recognisable, the weeding out of all 

 such animals must be regarded as the most im- 

 portant measure for the prevention of the dis- 

 semination of tuberculosis through milk. 



We must now pass on to a consideration of 

 some of the methods which are available for 

 obtaining germ-free milk, some of which are, how- 

 ever, attended with too great labour and incon- 

 venience to admit of practical application. Thus, 

 wishing to prepare some sterile milk without 



