374 BACTERIOLOGY. 



between 35 and 38 C. It grows, but more slowly, 

 at 17 C. Under 16 C. no growth is visible. 



It is not destroyed by freezing. When exposed to 

 65 C. its vitality is destroyed in five minutes. 



It is strictly aerobic, its development ceasing if the 

 supply of oxygen be cut off. 



It does not grow in an atmosphere of carbonic acid, 

 but is not killed by a temporary exposure to this gas. 

 It does not grow in acid media, but flourishes best in 

 media of neutral or slightly alkaline reaction. It is so 

 sensitive to the action of acids that at 22 C. its devel- 

 opment is arrested when an acid reaction equivalent to 

 0.066 to 0.08 per cent, hydrochloric or nitric acid is 

 present (Kitasato). 



In cultures the development of this organism reaches 

 its maximum relatively quickly, then remains stationary 

 for a short period, after which degeneration begins. 

 The dying comma bacilli become altered in appearance 

 and assume the condition known as "involution-forms." 

 (See Fig. 72.) When in this state they take up color- 

 ing-reagents very faintly or not at all, and may lose 

 entirely their characteristic shape. 



When present with other bacteria, under conditions 

 favorable to growth, the comma bacillus at first grows 

 much more rapidly than do the others; in twenty-four 

 hours it will often so outnumber the other organisms 

 present that microscopic examination would lead one 

 to take the material under consideration to be a pure 

 culture of this organism. This, however, does not last 

 longer than two or three days; they then begin to die, 

 and the other organisms gain the ascendency. This 

 fact has been taken advantage of by Schottelius 1 in the 



i Pwtsche me4, Wocbenschrift, 1885, No. 14. 



