INFLUKNn; OF TEMPERATURE 59 



The resistance of bacteria to low temperatures extends considerably below 

 zero Centigrade, FRISCH (I.) having shown that some species will bear cooling 

 down to - 1 10 0. for a short time without injmy. R. PICTET and E. YUNG (I.) 

 found that bacteria (species unknown) could bo kept at - 70 C. for 108 hours 

 and at - 130 C. for twenty hours without succumbing ; certain (unnamed) 

 species even withstanding the effects of a short exposure to -213 C. in 

 solidified oxygen. These facts are not merely of general biological interest, but 

 also, at the same time, important as regards the question of the suitable treat- 

 ment of stored food-stuffs. This will be discussed in a subsequent paragraph. 



Antithetical to these cold-loving bacteria is the Bacillus thermophilus, dis- 

 covered by MIQUEL (II.), which thrives and reproduces with great activity at 

 70 C., a temperature which instantly kills animal cells, coagulates egg albumin 

 and blood serum, and produces painful burns on the skin. When kept at 50 C. 

 this aerobic bacillus occurs as short rods, about i p. in thickness, which become 

 longer as the temperature rises, threads beginning to form at 60 C., and 

 constituting at 70 C. the sole occupants of the field. The lowest limit of 

 temperature at which development of this organism can be observed is about 

 42 C. ; above 72 C. the vegetative forms die off. This non-ciliated fission 

 fungus is but seldom met with in atmospheric dust, but is very frequent in 

 sewage, and therefore also in sewage-contaminated waters. It is likewise 

 present in the alimentary canal of human beings and mammals. This locality 

 seems to possess a highly suitable temperature for the growth of this saprophyte, 

 although accurate knowledge on the subject is still lacking. When the 

 temperature rises above 50 the medium undergoes putrefaction as a result of 

 the activity of the bacillus. 



Between Bacillus thermophilus and the aforesaid cold-loving species there 

 are numerous species forming intermediate links in the chain. In the case of 

 Forster's microbe, already mentioned, the highest limit of supportable tempera- 

 ture is 35 C., and it cannot retain its vitality when exposed, even for a few 

 hours, to a temperature of 35 to 37 C. GLOBIG (I.) isolated from garden soil 

 twenty-eight species of bacteria, each of which still developed luxuriantly at 

 60 C., whilst the minority were able to grow at even higher temperatures. In 

 connection with their occurrence in nature the question of the limits of tempera- 

 ture range of climate within which they can grow is of interest. In this 

 respect great differences were observed, one of them growing as well at 1 5 as 

 at 68 C., whilst most of the others required a temperature of over 50 C., and 

 one exhibited signs of development only when the temperature exceeded 60 C. 

 It must therefore be concluded that, under natural conditions, the reproduction 

 of these organisms proceeds only in the height of summer, when the soil is 

 sufficiently heated by prolonged sunshine. These warmth-loving bacteria are 

 not found in the ground exclusively. LYDIA RABINOWITSCH (I.) isolated from 

 the excrement of various animals, as well as from manures, milk, &c., eight 

 widely distributed species, for which the highest limit of temperature at which 

 growth was possible was found to be 75 and the minimum about 39 C. These 

 organisms are therefore able to reproduce freely in the alimentary canal of 

 warm-blooded animals and human beings. Warmth -loving fission fungi are also 

 riot infrequently encountered in sea- water. One example of this is afforded by 

 a phosphorescent bacterium found in the West Indies and described in chapter 

 xv. under the name of Bacterium phosphorescens. This inhabitant of the tropics 

 thrives best at 2o-3o C., and ceases growing at i5C. Living bacteria have 

 also been found in boiling springs, e.g. that discovered by Cortes and Garrigon 

 in the basin of a mineral spring, the temperature of which was 64 C. 

 J. KARLINSKY (I.) in 1895 discovered in the hot sulphur springs at llidze, near 

 Sarajevo, in Bosnia, two species of Schizomycetes which he named Bacterium 



