246 PATHOGENIC BACTERIA, 



with typical lepra lesions of all the viscera, especially 

 the cecum. 



While the lepra bacillus has much in common with the 

 tubercle bacillus, there is not the slightest evidence of 

 any real identity. It has already been shown that lepra 

 bacilli do not grow upon artificial media, and that they 

 cannot be readily transmitted by inoculation. The fol- 

 lowing description will show that the relation of the 

 bacilli to the lesions is entirely different from that of 

 the tubercle bacilli to the tubercles. 



Like the Bacillus tuberculosis, the Bacillus leprae proba- 

 bly only occurs in places frequented by persons suffering 

 from the disease. That individuals are infected by the 

 latter less readily than by the former bacilli probably 

 depends upon the fact that leprous infection seems to 

 take place most commonly by the entrance of the organ- 

 isms into the individual through cracks or fissures in 

 the skin, while the tuberculous infection occurs through 

 the more accessible respiratory and digestive apparatus. 

 Once established in the body, the bacillus by its growth 

 produces chronic inflammatory nodes the analogues of 

 tubercles. 



The nodes of lepra consist of various kinds of cells 

 and of fibres. Unlike the tubercles, the lepra nodes are 

 vascular, and much of the embryonal tissue completes 

 its formative function by the production of fibres. The 

 bacilli are not distributed through the nodes like tubercle 

 bacilli, but are found in groups enclosed within the proto- 

 plasm of certain large cells the " lepra cells." These 

 cells seem to be overgrown and partly degenerated lym- 

 phoid cells. Sometimes they are anuclear, sometimes 

 they contain several nuclei (giant-cells). 



Lepra nodules do not degenerate like tubercles, and 

 the formation of ulcers, which constitutes a large part of 

 the disease, seems largely due to the action of external 

 agencies upon the feebly vital pathological tissue, which 

 is unable to recover itself when injured. 



According to the recent studies of Johnston and Jamie- 



