528 Chaudhuri.—A Study of the Growth in 
agar added, and then plated. A very thin mycelium was produced, only 
just visible to the naked eye, but this grew very rapidly, and there was no 
difference in the diameters of the colonies incubated at the two temperatures. 
The following are the measurements in mm. from the fourth till the seven¬ 
teenth day : 
Days. 
PL 1 . 
PI. II. 
PI. III. 
PI. IV. 
PI. I. 
PI. II. 
PI. III. 
PI. IV. 
4 
10-0 
9-0 
9.0 
8.0 
10-0 
9-0 
10-0 
10-0 
5 
14-0 
13.0 
12-0 
12-0 
I 4*5 
12.5 
13.0 
14.0 
6 
18-0 
16-0 
I7.O 
I7.O 
16.5 
16.0 
i6-o 
17*0 
7 
22-0 
21-0 
21.0 
21-0 
22-0 
21-0 
20.0 
21.0 
8 
26-0 
26-0 
26-0 
25-0 
26.0 
26-0 
24-0 
25.0 
9 
30-5 
29-0 
29.O 
28-0 
31.0 
29.O 
27.0 
30-0 
10 
34 -o 
33 -o 
33 -o 
33 -o 
36.O 
32-0 
32.0 
34 -o 
11 
38-5 
37 -° 
37-5 
37-5 
39 °o 
37 -o 
37 -° 
38.0 
12 
4 i -5 
40-0 
40-0 
40-5 
4 2 *5 
40-0 
40*0 
4 I# 5 
!3 
45*5 
45 -o 
45.° 
45-5 
46-0 
45 *° 
43 '° 
45 -o 
I 4 
50.0 
5 1,0 
50.0 
49*5 
49-5 
48.5 
47.0 
49.0 
15 
54-5 
54 .o 
54-5 
53-5 
53 -o 
62*0 
52.0 
53 -o 
16 
58*5 
57 *° 
57*5 
57 -o 
57 -o 
56.0 
56.0 
56.0 
T 7 
61.5 
62.0 
61.5 
6o-o 
6o-o 
6o-o 
59’5 
6o-o 
Relation between Rate of Surface Spread of the Fungus 
and its Increase in Weight. 
The amount of spread may be taken as a satisfactory measure of 
growth when determining the effect of temperature with a definite medium 
of constant thickness. But when growth-data at a given temperature for 
different media are required it gives fallacious results. Almost the same 
rate of spread is found with normal N/2, N/4, N/8, and N/id Coon’s 
medium, though the determinations of dry weight show the increase in 
fungal material to be very different. The difference is especially marked for 
growth in liquid media. 
Fig. 6 shows graphically the relation between area and dry weight in 
Coon’s medium with agar at a temperature of 12 0 C. The diameters were 
measured on the 1st, 4th, 8th, nth, 14th, and 17th days, when also eight 
plates at a time were taken for dry-weight determination. The following 
gives an average figure for the area (diameter in mm. squared) and dry 
weight: 
1st Day. 
Area .... 
Weight .... 
nth Day. 
Area 
Weight . 
. . . . 0-0254 + 0-0014 grm. 
4 th Day. 
Area. 
Weight .... 
14//Z Day. 
Area 
Weight . 
. 0-0380 + 0.0021 grm. 
8 th Day. 
Area. 
Weight .... 
0.0148 + c-0012 grm. 
r ‘/th Day. 
A rea 
Weight . 
0 
. . . . 0-0557+ 0-0032 grm. 
