74 MILK HYGIENE 



On account of the great extent of tuberculosis among 

 cattle and on account of the frequency with which udder 

 tuberculosis occurs, it is to be expected, as is the case, 

 that market milk verj- often contains tubercle bacilli 

 in appreciable quantity. It is an established fact that 

 mixed milk from the co-operative creameries contributes 

 to a great degree to the spread of tuberculosis among 

 swine and calves. It has been proven, too, that feeding 

 the dirt removed by the milk separator (centrifugal 

 slime) to swine, may be dangerous. It is conclu- 

 sively established that the obligatory pasteurization of 

 skim milk in the various creameries, that has been 

 adopted in Denmark in recent years, has greatly aided 

 in checking the spread of tuberculosis among swine and 

 calves. 



It is quite natural, under these conditions, that it has 

 also been possible to show that milk sold in the cities 

 contains tubercle bacilli in considerable quantity. St. 

 Friis made some investigations of the milk supply of 

 Copenhagen in this connection; in testing samples of 

 milk from twenty-eight herds in Copenhagen and vicin- 

 ity, he found four tuberculous, while 33 samples from 

 small farms in Seeland were shown to be incapable of 

 producing tuberculosis when inoculated upon animals. 

 These results are better than those reached elsewhere 

 through similar investigations. In the table on page 75, 

 essentially after Klimmer, a review is given of such 

 results from different cities. 



These results were gained chiefly by intraperitoneal 

 inoculations of milk upon rabbits and guinea pigs and 

 are, therefore, to be regarded, to a great degree, as 

 authentic. 



The tubercle bacilli are sufficiently resistant to live 

 through the souring and other processes necessary in the 

 manufacture of milk into butter and cheese, so that but- 



