70 
IOWA ACADEMY OF SCIENCES. 
arbitrarily [it is true, the thermotolerant and the ther- 
mophilic. The optimum temperature of the former lies 
below 40°C. though growth may occur at much higher 
temperatures, even above 60°C. The optimum of the latter 
is above 40°C., this being the minimum for most forms. 
These temperatures, and favorable conditions for the 
growth of these forms, may be found in many places in 
nature besides the thermal springs. Even the soil when 
exposed to the direct rays of the sun is heated sufficiently to 
enable them to grow. Then, more important, heaps of 
decaying or fermenting organic matter such as silage or 
manure develop enough heat in their interior to give the 
optimum temperature for many. 
In order to determine something as to the thermophilic 
bacterial flora of the manure heap, the study here presented 
was undertaken. The study has not been completed, and 
notes are given on one only of the organisms isolated. 
Method of Isolation . — A rapidly fermenting heap of horse 
manure, with an interior temperature of about 58° C., 
was chosen for the study. Some of this material was 
removed in a sterile dish, washed with sterile water, and va- 
rious dilutions used for pouring plates. These latter were 
incubated at a temperature of 60° to 65° C. for eighteen 
hours and examined. A large number of colonies had made 
their appearance in every instance, and seemed to be quite 
uniform in character, i. e., probably one species was in pre- 
ponderance. Cultures were made from these colonies on 
various media, and these incubated at a temperature from 
60° to 62° C. A description of this organism follows. 
Careful comparison with published descriptions of va- 
rious thermophilic bacteria showed that probably this 
organism was the Bacillus thermophilus I. of Sames, iso- 
lated by him from earth. 
Morphology. — Rods, motile when young, 3-5 microns 
long, .6 microns broad, sometimes single, generally in 
chains of two to ten or more, ends of organism rather 
truncate. Stains easily and regularly with aniline dyes, 
* Hy g. Rundschau 8 : 320. 
