INFLUENCE OF TEMPERATURE. 45 



ing, non-motile bacilli, whose optimum temperature lies at 60 to 70, 

 but they still thrive at 34 to 44, although slowly, and best in ana- 

 erobic agar cultures (Z. H. XX, 154). The varieties are widely dis- 

 tributed, especially in feces. She has not undertaken a comparison 

 with the varieties described by previous authors. Other varieties 

 were isolated by Oprescu (A. H. xxxiu, 164). Some of the varieties 

 isolated by Schillinger appear more as abnormally thermotolerant 

 than thermophilic ; they grow well at 66, but better and with fer- 

 mentation at 37 (H. R., 1898, 568). 



By carefully raising and lowering the temperature, Dieu- 

 donne (C. B. xvi, 965) was able to increase the range of 

 temperature within which the anthrax bacillus could 

 thrive, at both its upper and lower limits. The anthrax 

 bacillus can gradually become adapted to a temperature of 

 42. Pigeons, which, according to the hypothesis of many 

 authors, are fairly immune to ordinary anthrax because of 

 their higher body temperature (42), die somewhat oftener 

 after inoculation with cultures adapted to higher tempera- 

 tures. Still more striking were the results when Dieu- 

 donne gradually acclimated anthrax bacilli to a tempera- 

 ture of 12, and found theyAild still kill frogs kept at 

 12. 



Temperatures somewhat below the minimum limit the 

 growth, but do not injure the variety concerned. Pe- 

 truschky has even kept bacteria in an ice-box (about 

 4 to 6) as a means of preserving not only the life but 

 also the virulence of certain varieties which rapidly die at 

 higher temperatures. They are first allowed to grow 

 for two days at 20 (streptococci, etc.). 



Also temperatures below zero injure bacteria, but do 

 so slowly and with a rapidity varying with different vari- 

 eties. Individual statements are given in the special part 

 regarding the most important pathogenic varieties. 



If temperatures 5 to 10 above the optimum are 

 allowed to operate upon cultures, they are injured in 

 various ways; some show lessened intensity of growth, the 

 virulence and the power of fermentation are reduced, also 

 the ability to form spores is gradually lost. Sometimes 

 the injury is more marked in one direction, sometimes in 

 another. 



If the maximum temperature is exceeded, the culture 

 dies, and for the psychrophilic varieties about 37 is quite 



