EFFECT OF TEMPERATURE UPON BACTERIA. 145 



Psychrophilic Bacteria. Minimum at 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. M.iguel has 

 described a certain bacillus thermophillm, which thrives 

 at from 42 to 72 C., its optimum being at 65 to 

 70 C., and found in cloacae, the contents of the intes- 

 tines, and in dirty water. Rabinowitsch has recently 

 described eight thermophilic facultative anaerobic 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 

 anaerobic agar cultures. They are found widely dis- 

 tributed in the feces. 



By carefully elevating or reducing the temperature 

 Dieudonn6 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. DieudonnS also 



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