PHYSIOLOGICAL RELATIONS 



observations on the above-mentioned organism are here presented 

 in tabular form. 



In the above case it happens that the optimum for germination 

 corresponds very closely with that for the formation of a visible 

 mycelium and for the beginning of spore production, but this will 

 not hold for all fungi. In general, the optimum temperature for 

 the bacteria and fungi with which the pathologist is concerned 

 would lie between 25 and 32 C., and it is customary to run an 

 incubator in which ordinary cultures are being kept for vigorous 

 growth and development at from 26 to 28 C. 



High temperatures. The thermal death points for vegetative 

 cells of the bacteria and fungi have been variously determined 

 to range from 40 to 75 C. As a rule, few fungi will grow 

 above 40, and to this temperature most of these organisms will, 

 after a time, succumb. Nevertheless, both fungi and bacteria are 

 able in one stage or another to survive considerable extremes of 

 heat and cold. The parasitic organisms in general are vegeta- 

 tively vigorous within far narrower limits than those of sapro- 

 phytic origin, which latter are, for the most part, in nature 

 subjected to greater extremes of conditions during the growing 

 period. 



