2jS BACTERIA 



spores (Babes and Crookshank). That the bacilli possess 

 spores is believed on account of the following facts: 



1. That tubercular sputum, when thoroughly dried, main- 

 tains its virulent character (Koch, Schill, Fischer, etc.). No 

 sporeless bacillus is known which can survive through 

 drying. 



2. That tubercular matter and cultures survive temper- 

 ature up to ioo° C. Non-spore-bearing bacilli and micro- 

 cocci are killed by being exposed for five minutes to a 

 temperature of 65-70" C, whereas spores of other bacilli 

 withstand much higher temperatures. 



3. Tubercular sputum distributed in salt solution does 

 not lose its virulence by being kept at 100° C. for one or 

 two minutes; sporeless bacilli certainly would (Klein). 



4. A solution of per-chloride of mercury does not kill the 

 tubercle bacilli, as it does sporeless bacilli (Lingard and 

 Klein). 



Koch and many bacteriologists have declared the bacillus 

 to be a " true parasite." Koch based this view upon the 

 belief which he entertained that the bacillus can grow only 

 between 30° C. and 41'^ C, and therefore in temperate 

 zones is limited to the animal body and can originate only 

 in an animal organism. ** They are," he said, ** true para- 

 sites, which cannot live without their hosts. They pass 

 through the whole cycle of their existence in the body." 

 But at length Koch and others overcame the difficulties and 

 grew the bacillus as a saprophyte. 



Schottelius ' has observed that tubercle bacilli taken from 

 the lung of phthisical persons buried for years still retains 

 its virulence and capability of producing tuberculosis upon 

 inoculation. He further shows that tubercular lung kept 

 in soil (enclosed in a box) shows a marked rise in temper- 

 ature. Klein quotes these experiments as indications that 

 '* tubercle bacilli are not trite parasites^ but belong to the ecto- 



^ Centralblatt. f. Bad. und Parasit., vol. vii., p. 9. 



