274 BACILLI PATHOGENIC IN MAN. 



or again in those where, as the result of their employ- 

 ment, there is constantly irritation of the respiratory 

 mucous memhrane. In how far, however, these supposed 

 predisposing causes can be experimentally proved, or 

 can be brought into unison with clinical experience, 

 must be for the present left in doubt. 



Bacillus lepra. 



In all forms of leprosy (Lepra tuberculosa, maculosa, 

 and anassthetica), and quite apart from the country in 

 which the disease has been acquired, whether in the 

 East, in Norway, or in other places where it is endemic, 

 we find in the affected organs numerous characteristic 

 bacilli, which were first described by Armauer, Hansen, 

 Occurrence of and Neisser. These bacilli have been demonstrated in 

 bacilli. the leprous tumours of the skin, in the mucous mem- 



brane of the mouth, palate, and larynx ; further, in the 

 peculiar interstitial affections of the peripheral nerves, 

 of the cornea, cartilage, and testicle ; in the lymphatic 

 glands, spleen, and liver ; in the anaesthetic form of 

 leprosy, for example, in the thickened ulnar nerve ; and 

 lastly, on several occasions, in the blood of lepers. On 

 making sections through the cutaneous nodules we see 

 that the tissue is infiltrated with numerous small round 

 or oval cells, which are more or loss completely filled 

 with bacilli ; the latter often lie in a thick mass in 

 various directions, they often appear arranged in a more 

 or less ray-like form radiating from the centre of the 

 cell ; at times they form parallel bundles. In the older 

 tumours the so-called true lepra cells are present in 

 large numbers, these cells being large, multi-nucleated, 

 and similar to giant cells, and also containing very 

 numerous bacilli in their interior. In part, however, 

 the bacilli also lie outside the cells in the lymphatic 

 spaces. Kecently Unna states that he has convinced 

 himself, from the examination of dry sections, that the 

 supposed cells containing bacilli are only masses of 

 bacilli which are held together by gelatinous material, 

 and that the greater number of the bacilli are free, and 



