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 Ziehl’s 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 lepree 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. 
