TUBERCULOSIS. 171 



and con. point more strongly in the negative than in the 

 positive direction. 



The fragments do not look like the spores of any other 

 organisms. When spores occur in the continuity of 

 bacilli, they are generally discrete oval refracting bodies 

 easily recognized. The fragments seen in the tubercle 

 bacillus are irregular and biconcave instead of oval, have 



.. *#&* 



dF5^& 



K##vW -> 



FIG. 55. Tubercle bacillus in sputum (Frankel and Pfeiffer). 



ragged surfaces, and are without the refraction peculiar 

 to the ordinary spore. 



The spaces between the bacillary fragments cannot be 

 made to stain like the spores of other species. Finally, 

 all known spores resist heat more strongly than the fully- 

 developed bacilli, but experimentation has shown that 

 these degenerative forms are no more capable of resist- 

 ing heat than the tubercle bacilli themselves. 



The organism is not motile, and does not possess 

 flagella. 



The tubercle bacillus is peculiar in its reaction to the 

 anilin dyes. It is rather difficult to stain, requiring that 

 the dye used shall contain a mordant (Koch), but it is also 

 very tenacious of the color once assumed, resisting the 

 decolorizing power of strong mineral acids (Ehrlich). 



