134 The American Naturalist. | February, 
colonies in the Gruber’s tubes showed that every colony buried 
in the gelatin was unable to develop further, and that only a 
few of the superficial ones reached a somewhat larger size and 
liquefied the gelatin. “Evidently a slight quantity of oxygen. 
remained in the tubes (it is impossible to pump out all the air) 
and this sufficed for the development of some of the colonies. 
The tiny, dot-shaped colonies under the mica, those in the 
Gruber’s tubes, and those which produced liquefaction on the 
uncovered gelatin were then studied carefully and found to be 
all of one sort. They were bacilli agreeing exactly in their 
morphological characters with the rods which had been ob- 
served previously in the wet rotten tuber. That the dot-shaped 
colonies in the Gruber’s tubes failed to develop further simply 
from lack of oxygen is best shown by the fact that after the 
opening of the tubes the growth of the colonies and the lique- 
faction of the gelatin proceeded so rapidly that within 12 hours 
the latter was completely liquefied, even at room temperatures. 
(9) Reducing and Oxidizing Power—In stab cultures in nutri- 
ent gelatin rendered blue by tincture of litmus, a confluent, 
dirty-white growth was formed in the canal, and at the same 
time the gelatin began to change from blue to red, comment- 
ing at the upper end of the stab. When this reddening had 
reaching the bottom of the tube the gelatin began to liquefy 
commencing at the upper end of the stab. Along with this 
liquefaction there was a complete bleaching of the litmus, the 
gelatin resuming its original yellow color. It could not be 
determined whether this reduction shouldbe referred to removal 
of oxygen or to the liberation of hydrogen. Nutrient gelatin 
stained red by carminic acid was also entirely bleached by 
this bacillus. 
(10) Fermentation Products and other Results of Growth : 
(a) Gas Production—The organism causes a copious evolu- 
tion of gas from potato tubers, living or steamed ; potato broth 
with dextrose; and dextrose solutions containing ammonium 
tartrate and mineral salts. This gas was determined to be CO:- 
No mention is made of any hydrogen. Possibly some was 
overlooked. 
