BACTERIUM LEPRJB 167 



does caseation occur. Giant cells are uncommon. 

 The bacilli produce these changes largely by poison 

 in their body and by mechanical irritation. There is 

 some reason to believe, by most recent researches, 

 that a soluble or extracellular poison is formed. The 

 bacteria are discharged from the patient by the 

 sloughing of wounds, especially the ulcers in the nose 

 and throat. The dressings and cloths used to wipe 

 the nose should be burned. Intimate contact, such as 

 sleeping with or kissing lepers, should be avoided, but 

 there is no proof that ordinary relations of human 

 life easily transmit the disease. The best diagnosis is 

 made by finding the rods in their peculiar cells, which 

 is best achieved by removing a piece of the skin growths. 

 Morphology and General Character. The leprosy 

 bacillus, like the tubercle bacillus, is stained with 

 difficulty, and belongs to what are called the acid-fast 

 bacteria. Methods similar to that described for the 

 tubercle bacillus must be used, but the determination 

 is by no means simple even to the most experienced 

 bacteriologists. The similarity to the tubercle bacillus 

 is further shown by the fact that the tuberculin skin 

 test is positive in lepers. A poison similar to tuber- 

 culin, called leprin, has been made by extracting 

 leprous tissue. It is only within the last five years that 

 the pure direct cultivation of Bacterium leprce has 

 been successful, and then only upon special media 

 with a very delicate technic. More about the 

 poisons will probably be learned in the near future. 

 The bacillus of leprosy is a straight rod with rounded 

 ends, a trifle smaller than the tubercle bacillus. Its 

 resistance to chemicals and heat is probably the 



