FERMENTS, ENZYMES, TOXINS AND PTOMAINS 55 



investigations of Globig/ Miquel,^ and Macfayden and 

 BloxalP 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^ 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, 

 the so-called normal water bacteria, that grow best at about 

 20° C. 



Cooperating Bacteria. — Under natural conditions it fre- 

 quently occurs that the development of one species or group 

 of species of bacteria is directly dependent upon the func- 

 tional activities of another totally distinct species, the 

 growth of one group resulting in conditions that are of vital 

 importance to the existence of the other. Such interdepen- 



1 Zeitsohrift fiir Hygiene, Bd. iii, S. 294. 



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

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



' Zeitsohrift fiir Hygiene u. Infecktionskrankheiten, Bd. xx, Heft. 1, 

 S. 154 to 164. 



