Staining 349 



0.2-0.5 p- in breadth. It commonly occurs in pairs, which 

 may be associated end to end, but generally overlap some- 

 what and are not attached to each other. ; Organisms found 

 in old pus and sputum show a peculiar beaded appearance 

 caused by fragmentation of the protoplasm and the presence 

 of metachromatic granules (Fig. 104) These fragmented 

 forms have been thought to be bacilli in the stage of spor- 

 ulation, and Koch originally held this view himself, though 

 later researches have not confirmed it. 



The tubercle bacillus forms no endospores. The frag- 

 ments thought by Koch to be spores are irregular in shape, 



Fig. 104. Tubercle bacillus in sputum (Frankel and Pfeffer). 



have ragged surfaces, and are without the high refraction 

 peculiar to spores. Spores also resist heat strongly, but the 

 fragmented bacilli are no more capable of resisting heat 

 than others. 



The bacilli not infrequently present projecting processes 

 or branches, this observation having changed our views 

 regarding the classification of the organism, which is prob- 

 ably erroneously placed among the bacilli, belonging more 

 properly to the higher bacteria and probably being related 

 to the actinomyces. 

 ( The organism is not motile, and does not possess flagella. 



Staining. The tubercle bacillus is difficult to stain, 

 requiring that the dye used shall contain a mordant (Koch) ; 



