MICROSPIRA COMMA. 481 



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 addition 

 of sulphuric acid alone. (See Indol Reaction.) 



(What does the presence of nitrites in these cultures 

 signify?) 



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, whitish, 

 non-glistening patch at and about the site of inocula- 

 tion. 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 pre- 

 vent development at a lower temperature, but does not 

 have this effect when the temperature is more favorable. 

 On solidified blood-serum growth is usually said to 

 be accompanied by slow liquefaction. I have not suc- 

 ceeded in obtaining this result on Loffler's serum, nor 

 have I detected anything characteristic about its growth 

 on this medium. 



The temperature most favorable for its growth is 

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

 at 17 C. Below 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. 



31 



