METHODS OF DIAGNOSIS, 259 



direct contact. There appears to be no doubt, however, 

 that on the one hand leprous subjects may bear children 

 free from leprosy, and that on the other hand, healthy 

 individuals entering a leprous district may contract the 

 disease, though this rarely occurs. Of the latter occurrence 

 there is the well-known instance of Father Damien, who 

 contracted leprosy after going to the Sandwich Islands. In 

 view of the fact that we must regard the bacillus as the 

 cause of the disease, it is highly probable that in certain 

 conditions it may be transmitted by direct contact, though 

 its contagiousness is not of a high order. 



In leprosy, therefore, there is an organism which is 



invariably present in the disease, and has a special relation 



to the changes in the tissues. This organism can be 



distinguished from all other known organisms, and is found 



in no other condition. Further, all the tissue changes in 



leprosy can be readily explained by the presence of a low 



form of irritation, such as is afforded by this organism. 



The evidence stated must be accepted as to its being the 



cause of the disease, though absolute proof is still wanting 



owing to failure to cultivate the organism outside the body. 



Methods of Diagnosis. Film preparations should be 



made with the discharge from any ulcerated nodule which 



may be present, or from the scraping of a portion of excised 



tissue, and should be stained as above described. The 



presence of large numbers of bacilli situated within the 



cells and giving the staining reaction of leprosy bacilli, 



3 is conclusive. It is more satisfactory, however, to make 



, microscopic sections through a portion of the excised tissue, 



i when the structure of the nodule and the arrangement of 



. the bacilli can be readily studied. The points of difference 



, between leprosy and tubercle have already been stated, 



and in most cases there is really no difficulty in distinguish- 



: ing the two conditions. 



