316 BACTERIOLOGY. 



color when subsequently treated with strong solutions 

 of the mineral acids and alcohol. Thus double-stained 

 preparations may be made by first staining sections or 

 cover-glass preparations in ZiehPs carbol-fuchsin solu- 

 tion or in an aqueous solution of methyl-violet, de- 

 colorizing in acid, washing in alcohol, and counter- 

 staining with methylene-blue or fuchsin. 



Biological Characters. Attempts to cultivate the bacil- 

 lus leprse have been frequently made, but so far with 

 only questionable results. None of the cultures ob- 

 tained have given positive results when inoculated 

 into animals. 



Pathogenesis. Numerous inoculation experiments 

 have been made on animals with portions of leprous 

 tubercles, excised for the purpose from lepers, but 

 although a few positive results have been reported, 

 there is no conclusive evidence that leprosy can be 

 transmitted to the lower animals by inoculation. The 

 inference that this bacillus bears an etiological relation 

 to the disease with which it is associated is based 

 entirely upon the demonstration of its constant pres- 

 ence in leprous tissues. 



The bacilli are found in all the diseased parts and 

 usually in large numbers, especially in tubercles on the 

 skin, in the conjunctiva and cornea, and the mucous 

 membranes of the mouth, gums, and larynx, and in 

 the interstitial processes of the nerves, the testicles, 

 spleen, liver, and kidneys. The rods lie almost exclu- 

 sively within the peculiar round or oval cells of the 

 granulation tissue which composes the leprous tubercles, 

 either irregularly scattered or arranged parallel to one 

 another. In old centres of infection the leprosy cells 

 containing the bacilli are larger and often polynuclear. 



