CULTIVATION OF LEPROSY BACILLUS. 409 



not killed when exposed to a temperature of 60° C. for thirty minutes. 

 They were killed when exposed to tlie same temperatui'e for sixty 

 minutes. 



The microorganism isolated from tlie nodule in' the thigh of Case G 

 is identical in its cultural characteristics witli that isolated from the 

 spleen in Case F. 



BACILLUS FROM CASE F. 



Morpliology. — The length of the organisms varies from 1 to 5 microns. 

 Stained with the method of Ziehl-Neelbon, the shortest forms are colored 

 uniforml}" throughout, as are also many of the long ones. In many 

 instances, however, certain portions of the hody of the bacteria are 

 more deeply stained than the remaining ones. Sometimes, especially 

 in the younger cultures, the center of the organism stains more deeply 

 than do the poles, which may be only very faintly colored. Other 

 individuals present a beaded appearance due to the alternate arrange- 

 ment throughout the body of deeply and lightly stained areas. Finall}', 

 a few forms were found in which the deeply stained portions were 

 situated in the poles. 



Various shapes have been seen. Some of the very smallest approach 

 the form of a coccus. The majority of the young bacteria are straight 

 0]' slightly curved rods. Long, slim forms are also encountered. No 

 ti'ue branching was observed and spore formation was absent. 



The character of the morphology is influenced considerably by the 

 nature of the medium upon which the organism is cultivated. The 

 bacillus is nonmotile. 



Stainiiuj reactions. — Smear preparations from cultures of all ages of 

 the microoi'ganism stain very faintly with the ordinary alkaline stains. 

 Preparations made from young cultures when stained with hot carbol- 

 fuchsin do not lose the stain when treated with Gabbet's solution. They 

 also retain it after being washed continuously for three minutes in 

 absolute alcohol. When treated for two minutes with a 5 per cent 

 solution of hydrochloric acid in alcohol, a large number lose the fuchsin 

 stain; there are others, however, which are not affected by this decoloriz- 

 ing agent. 



Older cultures are more susceptible to the acid-alcohol decolorizing 

 agents.- Preparations from a three month's old cultiire stained with the 

 carbo^ fuchsin solution were readily decolorized when treated with hydro- 

 chloric acid and alcohol, while smears from the same culture similarly 

 stained and treated with Gabbet's solution or with ahsolute alcohol 

 retained their color. 



The bacilli in smear preparations, from lesions in guinea pigs, are 

 acid fast when treated with hydrochloric acid-alcohol solution. Prepara- 

 tions from cultures of all ages were Gram positive in portions. By this 



