122 THE ROYAL SOCIETY OF CANADA 



ruber will ordinarily succumb only after being subjected to steam for 

 from one to six hours. These statements point to a recognition of 

 specific variations in thermal resistance on the part of endospores. 

 There is, however, a singular lack of definite data as regards the thermal 

 resistance of endospores in general and of investigations coordinating 

 these data regarding the resisting powers of the spores of individual 

 species — a search through Baumgarten's Jahresbericht for the last 

 ten years covered by that publication (i.e. for the years 1901-1910 

 inclusive) reveals not a single investigation of this nature. 



The sporadic, unscientific state of our knowledge in this respect 

 is exemplified by the contradictory views brought forward in explana- 

 tion of certain supposedly resistant bodies associated with Tubercle 

 bacilli. More particularly in old cultures or old foci of tuberculosis, 

 small round or oval bodies are found and the bacillus itself may take 

 on a beaded form. Young rods, at first Gram negative, lose this 

 character with age; these bodies are Gram positive. They may be 

 found in obsolescent, encapsulated, caseous tubercles in the lung when 

 the most careful staining fails to reveal a single tubercle bacillus. As 

 methods of staining this organism both in tissue and in smears have 

 been most fully elaborated, it does not seem possible that any bacillary 

 rods present escape detection. On the other hand matter free from 

 true bacilli but containing these resistant forms will set up typical 

 tuberculosis when inoculated into guinea pigs. These granules grown 

 upon a favorable medium, moreover, can be made to revert to the 

 typical acid-proof Gram negative form of the Bacillus Tuberculosis.^ 

 Do these bodies then represent resistant forms — spores — of the specific 

 organism of tuberculosis ? In contradiction it is urged that they have 

 not the full resistant power of true spores since subjection to a heat 

 of 80°C. will render this caseous matter innocuous. But there is no 

 conclusive evidence establishing a resistance to a temperature of 

 80°C. as the lower boundary of all true spore territory. Granting the 

 known variation in the powers of resistance between species there is 

 the possibility that the notable extremes of high resisting power may 

 have their counterpart in those of low resistance. If it were found, on 

 submitting the spore-bearing bacteria to a uniform heat test, that they 

 fell into a series varying from those with spores resisting the moist 

 temperature of boiling water, or even higher, down to those withstand- 

 ing heat a few degrees higher than that fatal to bacterial bodies, then 

 in this table we should include as true spores the beaded bodies of 

 B. Tubercle — the Much's granules of Hodgkin's disease, and the allied 

 forms seen in old tubercular foci, provided we find these possess higher 

 resisting powers than do the vegetative bacilli. In addition, this scale of 



iW. B. Wherry: Jour. Infect. Dis. Vol. XIII, 1913, p. 144. 



