302 



THE TUBERCLE BACILLUS 



[The results of the inoculation experiments carried out on rabbits by 

 Cobbett, A. S. Griffith and F. Griffith on behalf of the English Commission 

 may be summarized here. 



[The bovine tubercle bacillus produces a severe and fatal general tubercu- 

 losis whether inoculated sub-cutaneously, intra-venously or intra-peritoneally. 

 [The human tubercle bacillus very occasionally produces a fatal general 

 tuberculosis when inoculated intra-venously or intra-peritoneally but as a rule 

 the lesions found are those of a slight and retrogressive tuberculosis. Sub- 

 cutaneous inoculation never leads to a fatal result : for example, 125 rabbits 

 inoculated sub-cutaneously with doses varying from 1-100 mg. of culture 

 of the human tubercle bacillus and killed after 3-24 months all showed 

 retrogressive tuberculosis. 



[The avian tubercle bacillus usually produces a fatal general tuberculosis 

 by whichever of the three methods it be inoculated. This type is less virulent 



for rabbits than the bovine tubercle 



* bacillus and it causes generally less 



disease of the internal organs. ] 



6. Infection by feeding. The in- 

 gestion of tuberculous material 

 mixed with food does not always 

 lead to infection of the rabbit : 

 some animals entirely escape the 

 disease, others show lesions of the 

 alimentary and respiratory tracts 

 while the majority contract an 

 infection strictly limited to the 

 respiratory passages ( Weleminsky). 

 The sub -maxillary glands are first 

 infected then the cervical glands, 

 followed by the bronchial ; finally 



the pulmonary parenchyma is 



FIG. 192. An early lesion produced in the liver of n 4-4- nft ~\ r ^J rpr "Ui^'4- 



a rabbit 14 days after inoculation in the vein of an attacked. Ine rabbit IS more SUS- 



ear with 1 mg. of culture of avian tubercle bacilli, ceptible to the ingestion of bacilli 



An example of a "giant cell" produced by the avian -S . & . . , 



tubercle bacillus. The bacilli have been growing OI bovine Or avian Origin than 01 



abundantly within the "cell" and are very small. n r, P illi n f Tinman rni'm'n 



x 600. (Eastwood.) (See footnote p. 295.) \ Ol numan origin. 



[Cobbett, A. S. Griffith and F. 



Griffith found that feeding with bovine tubercle bacilli was always followed 

 by a progressive tuberculosis in rabbits while when fed with the avian 

 tubercle bacillus only one rabbit out of seventeen fed showed severe genera- 

 lized tuberculosis. Progressive tuberculosis cannot be produced in rabbits 

 by feeding them on human tubercle bacilli.] 



C. Dogs. 



Dogs may be infected by inoculating them with large doses of the 

 human tubercle bacillus but they are much more resistant to the avian 

 bacillus though not absolutely immune to it (Grancher and Hericourt). [The 

 dog is one of the few species of animals in which the effects produced by the 

 bovine and human tubercle bacilli are identical. Dogs " have shown them- 

 selves insusceptible to avian tubercle bacilli inoculated by the most severe 

 method and in relatively large doses " (work of the English Commission).] 



1. Sub-cutaneous inoculation. The disease following sub-cutaneous inocu- 

 lation is not necessarily fatal : it may remain localized or become a generalized 

 infection. [The English Commission found that the dog is resistant to the 

 sub-cutaneous inoculation of either the bovine or the human tubercle bacillus.] 



