DIFFERENTIATION OF LEPROSY AND TUBERCLE BACILLI. 225 
latter the most striking features were the large strongly 
stained lepra cells and globi. In the former, on the contrary, 
it is the intercellular bacilli and those contained in the minute 
cells which are stained well, while the large lepra cells are 
inconspicuous, being, for the most part, stained blue with a few 
scattered red-stained organisms. This would seem to indicate 
that there are considerable differences in the age and probably 
also in the activity of the bacilli. From what we know of 
other bacilli, it would seem probable that the scattered 
intercellular organisms are the youngest and most active, 
while the large masses are composed of older and possibly 
degenerated bacilli, or those which have developed a consider- 
able capsule. 
The resistance to decolourising agents has also served as a 
basis of distinction between the two varieties of bacilli, but is 
not reliable as an absolute criterion. The B. lepre appa- 
rently resists decoloration more vigorously than B. tuber- 
culosis. The remarks made above as to the reaction 
between number and rapidity of staining apply equally to 
decolorisation. 
Babes states that B. lepre in cover-glass preparations will 
resist decolorisation by strong nitric acid for one hour, while 
the tubercle bacilli seldom resist for more than half an hour. 
Not having any cover-glass preparations of undoubted leprosy 
material, it was impossible to confirm this statement; but the 
B. tuberculosis is certainly decolourised in the time. The 
method is, however, a very severe one, often resulting in the 
detachment of the film, and is obviously inapplicable to 
sections. 
Lustgarten proposed to distinguish between the bacilli by 
the greater resistance of B. leprz to the decolourising action 
of 1 per cent. hypochlorite of sodium. Wesener and 
Bonomé, however, have examined this method and rejected it 
as useless. 
Voltolini states that if, before staining, a cover-glass pre- 
paration of B. tuberculosis be exposed to the action of 
fuming nitric acid, the bacilli appear when stained as a row of 
VOL. XXXII, PART I1.—NEW SER. P 
