158 Isolating and Growing the Lepra Bacillus of Man. 
well formed and quite acid-fast. The lepra bacillus inoculated on to this 
medium at first grows extremely slowly, but later growth becomes faster, 
marked microscopic evidence being obtained in about four weeks. To the 
naked eye, growth is only just visible after about six weeks, appearing as 
a colourless film along the needle track. Attempts to sub-culture on to 
ordinary laboratory media are always negative. 
Experiments are now being carried out, using other organisms than the 
‘ tubercle bacillus for making the medium, and also testing various micro- 
organisms on the medium. 
In the near future it is hoped to prepare a vaccine from the ground-up 
lepra bacilli, for the treatment of man suffering from leprosy. An attempt 
to grow the rat lepra bacillus on the same medium will also be made if the 
material can be obtained. 
In conclusion, I may note that, working with Mr. Ingram, I have also 
succeeded in isolating and growing the acid-fast bacillus found in the 
intestine of cows in Johne’s disease. The first generation of this bacillus 
grows often long, with occasional branching and* club formation, in sub- 
cultures it gradually grows smaller, and in the second or third generation 
is about the size of the tubercle bacillus. The growth is only just 
visible to the naked eye, and sub-cultures on the ordinary laboratory media 
show no evidence of multiplication. Johne's bacillus grows somewhat more 
easily than Hansen’s lepra bacillus; the bacilli being well formed and quite 
acid-fast. The cultures were incubated at 40° C. It is hoped, when 
sufficient material is obtained, to prepare a vaccine for diagnostic purposes. 
Further details of these experiments will be published later. 
