TUBERCULOSIS. 217 



although the growths are as luxuriant as, or are actually 

 more luxuriant than ever. We have in fact a kind of 

 reversion to the saprophytic condition of the culture, a 

 condition accompanied by diminished parasitic virulence. 

 It is possible, therefore, that the higher temperature that is 

 met with in cattle along with other conditions there present 

 may have a distinct effect in diminishing the virulence of 

 the organism, whilst at the same time it may play an im- 

 portant role in causing its parasitic and vegetative activity 

 to be increased within the body of these animals, though 

 this is not necessarily accompanied by increased vegetative 

 activity outside the body. As Koch pointed out at the 

 International Medical Congress, of 1890, the tubercle cultures 

 from fowls were quite distinct and could not be passed 

 on as such from animals to animals of different species 

 or by growth at different temperatures, and he con- 

 cludes that although nearly related to the ordinary tubercle 

 bacillus they are specifically distinct. It should be noted, 

 too, that tubercle bacilli grown on glycerine agar are, 

 according to Nocard and Roux, somewhat shorter than 

 the bacilli met with in tubercular sputum, that they 

 also contain numerous ovoid spores, but that otherwise 

 they are exactly like those described by other observers in 

 various animals and on other media. As has been already 

 mentioned, there was necessarily a doubt whether any disease 

 could be tubercular if it was not possible by special methods to 

 demonstrate in histological preparations the presence of the 

 bacillus. This histological demonstration is, however, after 

 all, a clumsy method, and in many cases it has been found 

 possible to obtain demonstrations of the tuberculous nature 

 of a disease by inoculation experiments when the organisms 

 have been so few that they have escaped the notice of the 

 most careful observers. It may therefore be confidently 

 anticipated that more and more proof of the tuberculous 

 nature of lupus, scrofula, cold abscesses, and bone disease will 

 be gradually accumulated. 



As early as 1843 it had been demonstrated that tubercular 

 material from dead subjects when inoculated into rabbits 

 produced tuberculosis ; in 1865 these experiments were 

 repeated and extended by Villemin, and other observers have 

 from time to time confirmed the results that were then 

 obtained. Koch's observations and experiments have now, 



