BACILLUS LEPRE. 275 



lie usually in globular masses in the lymphatic channels ; 



but these statements require further proof in view of the 



unusual mode of investigation employed by Unna. The 



epidermic layer of the skin is 



always free from bacilli ; Babes 



alone has pointed out the presence 



of bacilli in the hair follicles, and 



in the sebaceous glands of the 



hair, and has thus shown that it 



is possible that the organisms may 



in this way reach the surface of the skin. 



The bacilli are 4 to 6 /*. in length, and less than Morphologka 

 1 A*, in breadth, resembling on the whole the tubercle characters - 

 bacilli, but not so irregular as regards length as these, 

 nor so often curved. Spores seem to be generally present, 

 but they are not so distinct as in the case of the tubercle 

 bacilli. The leprosy bacilli can be distinguished from 

 the latter by the fact that they take up the ordinary 

 aniline stains and the nuclear stains much more readily 

 than the tubercle bacilli. They can, however, be stained 

 in the same manner as the tubercle bacilli ; like these, 

 the leprosy bacilli alone among all the bacteria hold an 

 alkaline aniline stain, or one containing aniline oil, so 

 energetically that it is not removed on treatment with 

 strong acids. Hence in the case of the leprosy bacilli 

 we can employ the same method of double staining as. 

 in the case of the tubercle bacilli. The bacilli can be 

 stained red and the tissue blue, or violet and the tissue 

 brown. This is the best method of staining sections of 

 leprosy, and it shows most distinctly the individual 

 organisms. If we wish to distinguish between leprosy 

 bacilli and tubercle bacilli we place a dried cover glass 

 preparation for six to seven minutes in a dilute alcoholic^ 

 solution of fuchsine, decolourise for a quarter of a minute 

 in acid alcohol, wash in distilled water, and stain with 

 methylene blue. When treated in this way the leprosy 

 bacilli appear red on a blue ground, while the tubercle 

 bacilli have not taken up the red stain in this short 

 time (Baumgarten). 



All attempts at cultivation of the leprosy bacilli have 



