. -t-- ? point of maximum on tlue (left erd) ap- 



to furnish a criterion by which it " udped , a* least ir 



a general way, 1 ' the abscissa of this point approar 



es the minimum temperature value. Since the downward elc 



must v ? infinite for a range whose lower limit ie just > ale 

 minimum temperature, the nearer the actual slope approac>es in- 

 finity, the mere nearly does t>ie corresponding abscissa -value 

 approach that of the minimum temperature. " * follows cleanly 

 that the lowest temperature Lue her* considered 'as a middle 

 point of a 10-degree range), which is 13 c, is much more ^ear- 

 lv the mirimi smperature for enlargement for Phytophthora 

 than it is for an.y of the remaining three fungi. It is nearer 



the tempera ture minimum for Phomops is than for Pythiacystis a ^d 

 nearer the minimum for Pythiacystis than for "Piplodia. 



Since the graph of temperature coefficient as related 

 to temperature shows ordi nates that decrease in magnitude froa. 

 infinity to zero, it of course follows that the~e must he sere 

 point on every such graph, at which the ordinate Tcalue is unity. 



?or this point the coefficient value is 1.0 t i.e., a 

 temperature change from a very little below to a very little 

 above the abscissa value for this point is accompanied by no 

 change in the process rate at all. n i temperature value, 



or range, corresponding to this abscissa, or range of i as, 



therefore, is near tc the t emperature 6$i for the process 



consids^ed ; for lower temperatures the coefficient va2 

 all greater ' - er ones " - -Her 



than u^ity. 



These considerations i ly sst * 



here the -.it ion of teraperati or 



