GROWTH AND DEVELOPMENT OF BACTERIA. 35 



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

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

 a temperature as 70° C. and others at as low as 0° C. 

 The studies of Globig,' Miquel,^ and Macfadyen and 

 BloxalP have demonstrated that there exist in the soil, 

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

 tically everywhere, bacteria that under artificial culti- 

 vation show no evidence of life at a temj)erature lower 

 than 60° to 65° C, and would even grow at as high 

 a temperature as 70° to 75° C, degrees of heat suffi- 

 cient for the coagulation of albumin. Eabinowitsch' 

 lias 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 

 preceding investigators. The most favorable tempera- 

 ture for the development of pathogenic bacteria is that 

 of the human body, viz., 37.5° C. There are a num- 

 ber of bacteria commonly present in water, the so-called 

 normal ^vater bacteria, that grow best at about 20° C. 



In general then, from what has been learned, it may 

 be said that for the growth and development of bacteria 

 organic matter of a neutral or slightly alkaline reaction, 

 in the presence of moisture and at a suitable tempera- 

 ture, is necessary. From this can be formed some idea 

 of the omnipresence in nature of these minute vegetable 

 forms. Everywhere that these conditions obtain bac- 

 teria can be found. 



1 Glotiig : Zeitschrift filr Hygiene, Bd. iii. S. 294. 



2 Miquel ; Annales de MiorographU, 1888, pp. 4 to 10. 



3 Macfadyen and Bloxall; Journal of Path, and Baot., vol. iii. Part I. 



* Rabinowitscli : Zeitschrift fur Hygiene u. Infectionskrankheiten, Bd. xx. 

 Heft 1, S. 154 to 164. 



