46 BACTERIOLOGY. 



The investigations of Globig, 1 Miquel, 2 and Macfadyen 

 and Bloxall 3 have revealed the existence in the soil, 

 in water, in faeces, in sewage, in dust, and, in fact, prac- 

 tically everywhere, of bacteria that under artificial culti- 

 vation 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 suf- 

 fice 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 a lower temperature (34 to 44 C.), 

 as well as at the higher temperature mentioned by pre- 

 ceding investigators. 



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. 



Under natural conditions it frequently occurs that 

 the development of one species or group of species of 

 bacteria is directly dependent upon the functional ac- 

 tivities of another totally distinct species, the growth of 

 one group resulting in conditions that are of vital im- 

 portance to the existence of the other. This interde- 

 pendence of species is known as symbiosis. It is observed, 

 for instance, in the course of putrefaction, where, 



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



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



3 Macfadyen and Bloxall : Journal of Path, and Bact., vol. iii. part i. 



4 Rabinowitsch : Zeitschrift fiir Hygiene u. Infectionskrankheiten, 

 Bd. xx. Heft 1, S. 154 to 164. 



