104 THE MILK QUESTION 



may therefore pass from milk to cream and from cream to 

 butter. Schroeder has, in fact, shown that some of the 

 butter sold by dealers is very badly infected. According 

 to European investigators butter is more frequently in- 

 fected than milk. Schroeder estimates that butter con- 

 tains tubercle bacilli in sufficient numbers for their detec- 

 tion thirteen times for every ten times that they can be 

 found in milk. The reason for this is now perfectly evi- 

 dent. 



Investigators upon this special subject have found 

 tubercle bacilli to remain alive in butter a variable length 

 of time. Thus, Laser, twelve days; Heim, thirty days; 

 Gasperini found a reduction of virulence after thirty days; 

 but Dawson observed no reduction of virulence until three 

 months, and found the bacilli still alive in butter eight 

 months old. Broers found that tubercle bacilli will live 

 three days in milk, even when it has undergone changes 

 that make it unfit for use as food, twelve days in buttermilk, 

 and at least three weeks in butter. Schroeder found no 

 appreciable attenuation of tubercle bacilli in ordinary 

 salted butter in forty-nine days; that they were still highly 

 virulent after ninety-nine days, even though the butter 

 had become rancid and mouldy; and that they were alive 

 and capable of causing fatal tuberculosis in guinea-pigs 

 after one hundred and thirty-three days. Mohler found 

 that tubercle bacilli remained alive one hundred and fifty- 

 three days in butter held in cold storage under ordinary 

 commercial conditions. 



Cheese has also been found to contain tubercle bacilli. 

 In it they may live from thirty to forty days. The kinds 

 most dangerous are naturally the fresh cheeses, such as 

 cottage cheese. Cheeses which ripen slowly probably 

 contain no living tubercle bacilli when they reach the 

 consumer. 



We can draw no consolation from the fact that certain 

 kinds of oleomargarine, which is much used as a substitute 



