no MICRO-ORGANISMS AND DISEASE [chap. 



experimental test of drying and heating conclusively proves 

 that they are not comparable to spores. 



On the other hand the tubercle bacilli have been shown 

 experimentally (by Koch and others) to possess spores, 

 although it seems difficult to identify them under the micro- 

 scope. True, there are present in microscopic specimens made 

 of fresh material — e.g., tubercular sputum — bright granules 

 within many of the bacilli which might be taken for spores, 

 and in specimens stained after the customary method of 

 staining for tubercle bacilli numerous stained granules occur 

 in the bacilli — the bacilli appearing beaded — but, as has 

 been stated above, most of them are merely elementary 

 masses of protoplasm segregated in the bacilli. They occur 

 in some tubercle bacilli more numerously than in others — 

 e.g., in the tubercle bacilh of the human subject they are 

 common ; in the tubercular material of the fowl and in 

 artificial cultures they are sometimes seen with great regu- 

 larity, but there is no means available of identifying these 

 granules with spores. But by thorough drying of tubercular 

 material it can be shown that the tubercle microbes remain 

 uninjured, and that heating them up to ioo° C. for a minute 

 leaves the tubercle bacilli unharmed. 



Spores have been described also of some micrococci, but 

 here again certain differentiation of structure cannot be taken 

 as proving the existence of spores. The writer has exa- 

 mined very numerous preparations of the most varied cul- 

 tures of different species of micrococci, and the test of 

 drying and heating to 70° C. proves them barren of any- 

 thing comparable to the well-known spores present in some 

 species of bacilli. He also examined experimentally various 

 species of spirilla and agrees with Koch that no spore for- 

 mation can be demonstrated in them. We arrive then at 

 the conclusion that real spore formation, or the formation 



