CONCLUSIONS. 



"ro:n the results of the investigation of the temperature 

 relations of growth In pure cultures of fojur fungi, ( Pythia - 

 cfrstis c i t rophthora , Phytophthora t errestrla , Phomops is c itri 

 and Diplodi a n atalensis ), discussed in detail in the preceding 

 pages the following generalizations may be now brought to- 

 gether. 



It was indicated that there is the usual optimum 

 temperature above and below which the rate of enlargement 

 was smaller with higher or lower maintained temperatures. 

 With maintained temperature progressively higher than the 

 opiimum the growth rate is progressively smaller, and the same 

 is true also with temperatures progressively lower, but th\ s 

 decrease in rate is much more rapid in the first case. 

 Growth- temperature graphs (with temperatures as abciasas and 

 growth rates as ordinates) rise from left to right (from lower 

 to higher temperatures) at first slightly concave upward then 

 becoming convex till the optimu is passed and then fall rapid- 

 ly toward the temperature axis. 



It is to be emphasized that the optimum temperature 

 for the average rate of growth of a given fungus with a given 

 medium is not always the same for different lengths of ob- 

 servation periods. 



With culture periods of from three to six days and an 

 observation period 24-hours in length, it was found that In 

 general both the optimum and maximum temperatures for growth 

 shifted to lower temperatures for each successive observation 

 period. There was also corresponding displacement of the ap- 

 parent maximum temperature downward (from higher to lower tem- 

 peratures) with each successive observation period, ^hls 



