EFFECT OF TEMPERATURE UPON BACTERIA. 146 
Psychrophilic Bacteria. Minimum at 0° C., optimum 
at 15° to 20° C., maximum at about 30° C. To this 
class belong the water bacteria, such as the phosphor- 
escent bacteria in sea-water. 
Mesophilic Bacteria. Minimum at 10° to 15° C., 
optimum at 37° C., maximum at about 45° C. To 
this class belong all pathogenic bacteria, the conditions 
for their pathogenic action in man requiring acclima- 
tization to the temperature of the body. 
Thermophilic Bacteria. Minimum at 40° to 49° C., 
optimum at 50° to 55° C., maximum at 60° to 70° C. 
This class includes many soil bacteria and almost ex- 
clusively spore-bearing bacilli. According to Globig, 
there are about thirty species of bacteria capable of de- 
velopment at 60° C. and a few at 70° C. Miguel has 
described a certain bacillus thermophillus, which thrives 
at from 42° to 72° C., its optimum being at 65° to 
70° C., and found in cloace, the contents of the intes- 
tines, and in dirty water. Rabinowitsch has recently 
described eight thermophilic facultative anaérobic spe- 
cies, all spore-bearing, non-motile bacilli, the optimum 
temperature of which is from 60° to 70° C., though 
they grow slowly at from 34° to 44° C., and best on 
anaérobic agar cultures. They are found widely dis- 
tributed in the feces. 
By carefully elevating or reducing the temperature 
Dieudonné has succeeded in increasing the limits within 
which a variety of bacteria will grow. Thus, anthrax 
was gradually made to accommodate itself to a tem- 
perature of 42° C., and pigeons, which are compara- 
tively immune to anthrax, on account of their high 
body temperature (42° C.), when inoculated with this 
anthrax succumbed to the infection. Dieudonné also 
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