220 CHARLES SLATER. 
These criteria have been sought in differences in— 
1. The size of the bacilli. 
2. The shape. 
3. The staining properties, including the resistance to de- 
colorisation. 
4, The numbers and distribution of the bacilli. 
The differences based on the number and distribution will 
be found fully discussed in a paper written in association with 
Dr. Delépine (‘ Trans. Path. Soc.,’ 1891). 
While all observers speak of the B. lepre as resembling in 
size the B. tuberculosis, yet some, such as Fliigge, give 
measurements for the former which are considerably greater 
than those given for the latter. Bonomé, on the other hand, 
speaks of the leprosy bacillus as shorter and thicker than B. 
tuberculosis. 
There is also a general consensus of opinion that the B. 
lepre is less variable in length and more rectilinear (Koch, 
Fliigge, Babes) ; but Baumgarten confesses himself unable to 
establish any fundamental differences on these grounds, and, 
considering the extreme variability of the B. tuberculosis 
in various specimens of sputa, &c., it would be impossible to 
lay much stress on these differences. 
According to Neisser the B. lepre possesses pointed extre- 
mities, while Bonomé, on the other hand, regards a swollen 
pole as a distinctive mark of the bacillus. In the specimens 
obtained from the present case there is a decided enlargement 
of the poles of the bacilli, and in rapidly stained specimens 
the extremities are more strongly stained than the inter- 
mediate portions. 
The possession of a capsule seems to be common to both 
organisms, 
It is to the variations in the staining properties that most 
attention has been paid, and differences sought in— 
1. The different staining properties of various dyes, and of 
the various solutions of these dyes, whether made with aniline 
oil, alcohol, water, &c. 
2. The rapidity of the staining. 
