FERMENTS, ENZYMES, TOXINS AND PTOMAINS 57 



functions of these organisms is the temperature under which 

 they exist. The extremes of temperature between which 

 the majority of bacteria are known to grow range from 5.5 

 to 43 C. At the former temperature development is hardly 

 appreciable; it becomes more and more active until 38 C. 

 is reached, when it is at its optimum, and, as a rule, ceases 

 at 43 C.; though species exist that multiply at as high a 

 temperature as 70 C. and others at as low as C. The 

 investigations of Globig, 1 Miquel, 2 and Macfayden and 

 Bloxall 3 have revealed the existence in the soil, in water, 

 in feces, in sewage, in dust, and, in fact, practically every- 

 where, of bacteria that under artificial cultivation show no 

 evidence of life at a temperature lower than 60 to 65 C., 

 and will even grow at such high temperatures as 70 and 

 75 C., a state of affairs almost paradoxical, inasmuch as 

 these are temperatures that suffice for the coagulation of 

 albumin, and, in consequence, are generally incompatible 

 with life. Rabinowitsch 4 has likewise described a number 

 of species of these thermophilic bacteria, as they are called; 

 but states that it was possible in her experiments to obtain 

 evidence of their growth at the lower temperature (34 to 

 44 C.), as well as at the higher temperature mentioned by 

 preceding investigators. It is possible that this peculiarity 

 is but a manifestation of adaptation to environment and 

 not an essential to the life processes of these species. 



The most favorable temperature for the development of 

 .pathogenic bacteria is that of the human body, viz., 37.5 C. 

 There are a number of bacteria commonly present in water, 



1 Zeitschrift fur Hygiene, Bd. iii, S. 294. 



2 Annales de Micrographie, 1888, pp. 4 to 10. 



3 Journal of Path, and Bact., vol. iii, Part I. 



4 Zeitschrift fur Hygiene u. Infecktionskrankheiten, Bd. xx, Heft. 1, 

 S. 154 to 164. 



