338 BACTERIOLOGY. 



tion of the casein. It retains its vitality under these 

 conditions for about three weeks or more. The blue 

 color of milk to which neutral litmus tincture has been 

 added is changed to pink after thirty-six or forty-eight 

 hours at body temperature. 



Its growth in peptone solution, either that of Dun- 

 ham (see Special Media) or the one preferred by Koch, 

 viz., 2 parts Witte's peptone, 1 part sodium chloride, 

 and 100 parts distilled water, is accompanied by the 

 production of both indol and nitrites, so that after 

 eight to twelve hours in the incubator at 37 C. the 

 rose color characteristic of indol appears upon the addi- 

 tion of sulphuric acid alone. (See Indol Reaction.) 



In peptone solution to which rosolic acid has been 

 added the red color is very much intensified after four 

 or five days at 37 C. 



Its growth on potato of a slightly acid reaction is 

 seen after three or four days at 37 C. as a dull, whit- 

 ish, non-glistening patch at and about the site of inoc- 

 ulation. It is not elevated above the surface of the 

 potato, and can only be distinctly seen when held to the 

 light in a particular position. Growth on acid potato 

 occurs, however, only at or near the body temperature, 

 owing probably to the acid reaction, which is sufficient 

 to prevent development at a lower temperature, but 

 does not have this effect when the temperature is more 

 favorable. 



On solidified blood-serum the growth is usually said 

 to be accompanied by slow liquefaction. I have not 

 succeeded in obtaining this result on Loeffler's serum, 

 nor have I detected anything characteristic about its 

 growth on this medium. 



The temperature most favorable for its growth is be- 



