displacement was much more pronounced between the first and 

 second 24-hour periods than between any other two consecutive 

 periods except for Phytophthora. 



A comparative study of the growth-temperature graphs 

 of the four fungi for the second 24-hour period shows that the 

 total range of temperature within which growth rate values are 

 one tenth or mere of the maximum rate, Includes from 32,5 to 

 37 centigrade degrees of the temperature scale. Of this range 

 from 70 to 80 percent Is below and therefore only from 20 to 

 30 percent is above the optimum temperature for growth. 



With comparatively low temperatures the growth rate in- 

 creases with the age of the culture throughout the culture 

 period, and with the highest temperatures it decreases through- 

 out the culture period, this decrease soon bringing the value 

 to zero. With a small range of Intermediate temperatures the 

 rate first Increases with time and then remains constant, os- 

 cillates or decreases. 



The 10-degree temperature coefficient (Qio) * or each 

 of tha four fungi has a hlfeh value at the lowest range studied 

 and decreases progressively through lower values to zero. 

 The form of the graph representing the value of the temprrature 

 coefficient as related to different ranges of maintained tem- 

 perature shows that the value of the temperature coefficient 

 must begin with Infinity for some low range, mus^ pa3s through 

 all finite valtes and then must reach zero for some higher range. 

 For growth- temperature relations of this type the range for 

 which the coefficient Is t/nlty will Include the optimum tem- 

 perature, the range for which the coefficient 5 s infinity will 

 include the minimum temperature and the range for which the 

 coifflclent Is zero will Include the maximum temperature. 



The use of the coefficient temperature graphs fur- 





