Lesions 



703 



seems to be largely due to the injurious action of external agencies 

 upon the feebly vital pathologic tissue. 



According to the studies of Johnston and Jamieson,* the bacterio- 

 logic diagnosis of nodular leprosy can be made by spreading serum 

 obtained by scraping a leprous nodule upon a cover-glass, drying, 

 fixing, and staining with carbol-fuchsin and Gabbet's solution as 

 for the tubercle bacillus. In such preparations the bacilh are pres- 

 ent in enormous numbers, forming a marked contrast to tuber- 

 culous skin diseases, in which they are very few. 



Fig. 284, — Lepra anaesthetica (McConnell). 



In anesthetic leprosy nodules form upon the peripheral nerves, 

 and by connective-tissue formation, as well as by the entrance of 

 the bacilh into the nerve-sheaths, cause irritation, followed by 

 degeneration of the nerves. The anesthesia following the peripheral 

 nervous lesions predisposes to the formation of ulcers, etc., by allow- 

 ing injuries to occur without detection and to progress without 

 observation. The ulcerations of the hands and feet, with frequent 

 loss of fingers and toes, follow these lesions, probably in the same 

 manner as in syringomyelia. 



The disease usually first manifests itself upon the face, extensor 

 surfaces, elbows, and knees, and for a long time confines itself to 

 * "Montreal Med. Journal," Jan., 1897. 



