142 SPECIAL BACTERIOLOGY . 



that in fourteen samples of butter he found genuine tubercle bacilli, 

 capable of causing infection. Rabinowitsch, in eighty samples of 

 butter that he examined, did not find the Koch bacilli once, and he 

 considered that the positive results obtained by others were due to 

 the acid-resisting tubercle-like bacilli previously discovered by him 

 being mistaken for genuine tubercle bacilli. 



Petri's results occupy an intermediate position between those of 

 Obermiiller and Rabinowitsch. He found genuine tubercle bacilli 

 in 30 per cent., and the acid-resisting tubercle-like bacilli in 60 per 

 cent, of the samples examined. 



Horman and Morgenroth conducted a series of investigations 

 recently, and in ten samples of market butter examined they found 

 genuine tubercle bacilli in three of the samples (see Photomicrograph 

 of same, Plate III., Fig. 18), and in some of the samples, Rabino- 

 witsch's acid-resisting bacilli ; and in one of the experiments the 

 resisting bacteria and genuine tubercle bacilli were found associated 

 together. Glycerine agar was of no use as a culture media ; blood 

 serum, with the addition of 5 per cent, of glycerine, being found the 

 best medium in these investigations. 



The acid-resisting tubercle-like bacilli found in butter are 

 described by Horman and Morgenroth as follows : 



Microscopical Appearances. Slender rods, similar to the Koch's 

 bacillus of tuberculosis in form, slightly bent, and sometimes the end of 

 the rod is thickened. 



Motility. Non-motile. 



Staining Reactions. When stained by Gunther's method for 

 tubercle bacilli, they are not decolorized, but their resistance is not so 

 pronounced as with Koch's bacilli, as on the edges of the cover-glass 

 and contact specimen of colonies many of the rods are stained slightly 

 blue. In old cultures unstained portions in the stained rods were often 

 observed. The reaction with the Gram method is positive. 



Biological Characteristics. On Gelatine Plates the growth 

 is very slow. The deep-lying colonies are round, glistening, of 

 a light-yellow colour, and finely granular throughout. The 

 superficial colonies are also round, transparent, and possess irregular, 

 finely serrated margins. 



The gelatine is not liquefied. 



In Gelatine Stab Cultures a growth occurs along the middle track, and 

 after a long time a thick coating develops on the surface. 



On Agar oblique surface Cultures in twenty-four hours, at incubator 

 temperature, a white, creamy coating develops on the surface of the 



