296 MANUAL OF BACTERIOLOGY. 



mammalian tuberculosis. Rabbits are somewhat susceptible, though less 

 so than to mammalian tuberculosis. 



Pseudo-tuberculosis. Guinea-pigs and other rodents sometimes pre- 

 sent lesions macroscopically very similar to those of tuberculosis, in 

 which, however, the tubercle bacilli cannot be found. These affections 

 appear not to be tuberculosis at all, and their nature is not well under- 

 stood. Several organisms have been found in them, all of which are 

 entirely unlike the tubercle bacillus. 



Bacillus leprae (of leprosy). A slim bacillus about 4/^ 

 in length. It is probably not motile. It is uncertain whether 

 or not it forms spores. It stains by the Gram and the 

 Weigert fibrin method, and it is also colored by the methods 

 used for staining the tubercle bacillus. It takes the dye, 

 however, more readily than the tubercle bacillus. In stained 

 preparations it appears very similar to the tubercle bacillus, 

 and resembles it in having alternate colored and unstained 

 spots. Although several observers have reported success 

 in attempts to cultivate the bacillus of leprosy, their claims 

 have been disputed. The results of inoculation into man 

 and the lower animals of material coming from cases of 

 leprosy have also been uncertain. The bacillus of leprosy 

 has been found so constantly in the tissues of those having 

 the disease that it is generally admitted to be the specific 

 cause. The skin and the peripheral nerves are the parts 

 most affected, although other tissues and the internal viscera 

 may be involved. A granulation tissue, forming nodules 

 and thickenings, appears in the affected parts. The bacilli 

 are found in large numbers in the nodules, partly outside of 

 the cells, but mostly within the cells. It is still uncertain 

 whether or not the disease can be transmitted directly from 

 one individual to another, in extra -uterine life, or whether 

 it can be inherited from the parents. However, no explana- 

 tion can be given for the appearance of the infection in any 

 patient, except communication with some other case. 

 Transmission by contact seems at any rate not to take place 

 easily. 



