tw 



replot the graphs ui I e values thus derived. T, Ls treat- 

 ment removes apparent differences in curvature due to differ- 

 ences in the magnitudes of the max.' >rdi ates. Such re" 

 tive graphs for the second 24-hour ol ! :- period for each 

 fungus ar-3 presented, in figures 6 and 7. Constructed in this 

 way, the unit cf growth rate is different for the different 

 graphs, being always the maximum value for that fungus, but * 

 value is always considered as unity , hence all the graph max- 

 ima appear to he equal for these graphs. T e upward and down- 

 ward slopes cf these four graphs are strictly comparable as to 

 direction or angle, always with reference, not to actual growth 

 rates in millimeters, but to relative growth rates, in terms 

 of the corresponding maximum rate. 



Referring to figures 6 and 7, the relative degrees of 

 steepness of the graphs are nearly the same for the sub-optimal 

 region, and the same is true for the supra-optimal region, ex- 

 cepting that the graph for "Diplodia is here ? at less steep 

 than the other three. The four graphs differ considerably in 



other details, however, mainly in regard to total temperature 

 range and in regard -co minimum, optimum and maximum temperature 

 values. 



It is to be noted that if the entire graph for Phytoph- 

 thora -.vera moved to the left through 4 degrees of temperature, 

 e. g. , if all the rates for this funpua were plotted at te - 

 peraturea 4 degrees lower, this graph would follov. closely the 

 actual curve for Pythiacyatis except that the first part of 

 the downward slope is a littla steeper. The difference in the 

 two curves is therefor- ily one of location of the tempera- 

 ture r-a.nge and the actual values cf tl e increments. The 



i 



