OF BUTTER 563 



caused tuberculosis in guinea pigs. Schroeder 1 reports that 

 when cream is separated from milk infected with Bacillus tuber- 

 culosis, either by gravity or by centrifugal force, it also con- 

 tains these germs, and that butter made from such cream con- 

 tains the tubercle bacillus as determined by testing it with guinea 

 pig inoculation. Broers 2 found that tubercle bacilli will live three 

 days in milk, even when it has undergone changes that make it 

 unfit for use as food, and twelve days in buttermilk, and that 

 they remain virulent three weeks in butter. Cornet 8 reports that 

 Laser could find no live bacilli in butter after twelve days, that 

 Heine records that all tubercle bacilli eventually die in butter 

 and that their maximum life in it is thirty days, that Gasperini 

 found a reduction of virulence after thirty days, though the 

 bacilli were still alive after 120 days, and that Dawson did not 

 observe a reduction of virulence until after the passage of three 

 months, and claims to have produced tuberculosis in a guinea 

 pig by inoculating it with butter eight months old. Schroeder 

 and Cotton 4 state that living tubercle bacilli will retain their 

 infective properties for at least 160 days in salted butter when 

 kept without ice in a house cellar. They fed over 60 guinea 

 pigs, from time to time up to 100 days, with butter from a cow 

 infected with tuberculosis. With the exception of five that died 

 prematurely, and one that was killed, all died with generalized 

 tuberculosis. Swithinbank and Newman 5 tested 498 samples of 

 market butter (in England) and found 76 samples or 15.2 per 

 cent to contain tubercle bacilli. Schroeder 1 states that since salt 

 has distinct though weak germicidal properties, tubercle bacilli 

 in heavily salted butter may live only a short time, while in 

 unsalted butter they may live and remain virulent indefinitely. 

 No appreciable attenuation of tubercle bacilli occurs in ordinary 

 salted butter in 49 days, even though the butter has become 

 rancid and moldy. They are still alive and capable of causing 

 rapidly fatal tuberculosis in guinea pigs after 133 days. Mohler 

 showed that 153 days is not long enough to kill them in butter 

 held in cold storage under ordinary commercial conditions, and 



1 Schroeder, Milk and Its Products as Carriers of Tuberculosis Infec- 

 tion, U. S. Dept. of Agr. B. A. I. Circular 143, 1909. 



2 Broers, Zeitschrift fuer Tuberkulose, Vol. 10. No. 3, 1907. 



Cornet, Die Tuberkulose, Second Edition, Vol. 1, 1907, pp. 122-123. 

 4 Schroeder and Cotton, The Relation of the Tuberculous Cow to 

 Public Health, U. S. Dept. Agr. B. A. I. Circular 153. 



6 Swithinbank and Newman, Bacteriology of Milk, 1903, p. 221. 



