198 BACTERIOLOGY FOR NURSES 



12 and 36 C., the optimum temperature being 25 C. Neither 

 the avian nor the fish tubercle bacilli are pathogenic for man. 



OTHER ACID-FAST BACILLI 



Bacillus of Leprosy. Hansen in 1874 reported the presence 

 of a bacillus in the tubercles of leprous individuals which somewhat 

 resembled the tubercle bacillus. Later many other observers con- 

 firmed Hansen's report. In tissue sections the bacilli appear as 

 thin rods generally within the cells of the granulation tissue and 

 are often so numerous that the cell structure is hidden ; usually 

 they are arranged parallel to one another and present the appear- 

 ance of small bundles. They take up the basic anilin dyes more 

 readily than the tubercle bacilli, but like them they resist decolori- 

 zation with the mineral acids and alcohols. The organisms 

 differ from the tubercle bacilli in that they grow with difficulty 

 on artificial culture media and are much less if at all pathogenic 

 for the lower animals. 



In 1908 certain workers succeeded in growing an acid-fast 

 organism on plain agar in symbiosis with ameba and other bacteria, 

 and then by killing the other organisms by means of heat they 

 obtained a pure culture of " acid-fast " bacilli. There is no satis- 

 factory evidence, however, that such organisms will reproduce 

 the disease in experimental animals. 



The negative results following attempts to produce the disease 

 by inoculations of leprous tissue have led to the assumption that 

 the bacilli in such tissue must be for the most part dead. An 

 apparently successful attempt was made upon a criminal in the 

 Sandwich Islands, who obtained pardon on condition that he allow 

 himself to be inoculated with leprosy. He consented and the 

 disease did develop two or three years later. The experiment is 

 open to objection, however, because the man had, before inocula- 

 tion, been frequently in contact with lepers and had thus been 

 exposed to the infection in a natural way. 



It has been supposed by some observers that leprosy is a form 

 of tuberculosis. There is little ground for the supposition, although 



