Culture of Verticillium albo-atrum , B. et Br. 529 
It will be seen from the graph that the area curve more or less follows 
the compound interest law, at least for the period when the fungus is grow- 4 
ing vigorously, but the dry-weight curve runs almost in a straight line. 
The graph in Fig. 7 shows the increase in mycelial ‘ spread 5 obtained by 
mm} 
4200 
3800 
5200 
2600 
2000 
1400 
800 
200 
mgnn. 
-55 
-47-5 
-40 
-32-5 
-25-0 
-175 
-10-0 
-2-5 
area-i 
/ 
p 
/ ^ 
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/ / 
/ / 
/ 
/ 
/ 
Dry 
Wt 
/ / 
// 
// 
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/ / 
/ / 
/ 
/ 
t 
/ 1 
—fi 
// 
// 
// 
s 
r p 
/ / 
/ / 
/ / 
/ / 
/ / 
/ / 
/ / 
> / 
/ 
/ 
/ 
/ 
/ i 
/ / 
/ / 
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/ 
/ 
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/ J 
Q y 
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Days 3 5 I 9 11 15 15 IT 19 
Fig. 6. Curves showing the relation between the daily increase in dry weight of V. albo- 
atrum in Coon’s liquid medium, and the daily increase in ‘ spread ’ of the mycelium on the same 
medium with the addition of agar. The scale represents area covered by the mycelium as given in 
terms of the square of the diameter measured in mm. The vertical scale on the left represents mm. 2 , 
that on the right milligrams. 
measuring diameters daily up to ten days at different temperatures. At 
the end of that period the dry weight for the total growth was determined. 
The area curve and dry-weight curves are very much alike, and it is only in 
this case where we are estimating the effect of different temperatures that 
the spread is a satisfactory measure. By following the daily growth curves, 
