GROWTH AND DEVELOPMENT OF BACTERIA. 35 



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

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

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

 The studies of Globig, 1 Miquel, 2 and Macfadyen and 

 Bloxall 3 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 temperature 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 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 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 water 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 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. 



