34° PATHOGENIC BACTERIA. 



to that upon agar-agar. In puncture-cultures most of the 

 growth is on the surface in the form of a whitish, or 

 grayish, or yellowish folded layer. In the depths of the 

 gelatin the development occurs as a granular rather thick 

 column. The medium is hot liquefied. 



Bouillon is not* clouded; no superficial growth occurs. 

 The vegetation occurs only at the bottom of the tube in 

 the form of a powdery sediment. 



Czaplewski found that the bacillus stained well with 

 Loffler's methylen-blue, and with the aqueous solutions 

 of the anilin dyes. It also stains by Gram's method, and 

 has the same resisting power to the decolorizing action 

 of mineral acids and alcohol as the lepra bacillus as seen 

 in tissue. The young bacilli color homogeneously, but 

 older ones are invariably granular. They are usually 

 pointed at the ends when young, but may be rounded or 

 knobbed when older. The more rapidly the bacillus 

 grows, the longer and more slender it appears. 



All attempts to infect the lower animals with leprosy, 

 either by the purulent matter or solid tissue from lepers, 

 or by inoculating them with the supposed specific bacilli 

 that have been isolated, have failed. 



Ducrey seems to have cultivated the lepra bacillus in 

 grape-sugar, agar, and in bouillon "m vacuo." His 

 results need confirmation. Very few instances are re- 

 corded in which actual inoculation has produced leprosy 

 in either men or animals. Arning was able to secure 

 permission to experiment upon a condemned criminal in 

 the Sandwich Islands. The man was of a family entirely 

 free from disease. Arning introduced beneath his skin 

 fragments of tissue freshly excised from a lepra nodule, 

 and kept the man under observation. In the course of 

 some months typical lesions began to develop at the 

 points of inoculation and spread gradually, ending in 

 general lepra in the course of about five years. 



Melcher and Artmann introduced fragments of lepra 

 nodules into the anterior chambers of the eyes of rabbits, 

 and observed the death of the animals after some months 



