Brown. — Studies in the Physiology of Parasitism. VIII. 107 
Average length of germ- tube ( in 
Drop. Conductivity. micrometer divisions — av. of 25 
measurements). 
12 hrs. 
16 hrs. 
24 hrs. 
36 hrs. 
Distilled water 
0.8 
0.16 
0-2 2 
0.20 
0 
+. 
Os 
Tap- water 
48-0 
0*00 
0-00 
0-00 
— 
Drops on Cereus petal 
i -7 
0*2 2 
0-24 
0*58 
o-8o 
99 99 
3-5 
o-6o 
1-46 
2.32 
— 
99 yy 
4*5 
1. 00 
— 
3 * 3 2 
3 * 4 8 
9’ 99 
4.8 
0-76 
1.66 
2-60 
2.92 
99 99 
4.9 
070 
— T',/. 
2.44 
2.80 
9 9 9 9 
8.4 
2.16 
3. °° 
5*oo 
— 
9 9 9 9 
8,6 
1.50 
2.84 
4-28 
— 
9 9 99 
9 * + 
2-02 
— 
4-28 
5.16 
9 9 • 99 
9-5 
2.O4 
2.72 
3.88 
5 * 12 
9 9 9 9 
1-84 
2-64 
3 * 9 2 
6-12 
99 9 9 
14.2 
2-24 
— 
5.88 
8-6 
9 ' 99 
22.7 
2.92 
— 
6-8 
10-20 
99 9 9 
26-1 
2.48 
5.12 
c. 10 
10-20 
9 9 99 
2 7 -.4 
2.52 
5;°4 
c. 10 
10-20 
9 9 99 
32.° 
3-00 
— 
c. 10 
10-20 
9 9 99 
3 2 * 1 
2.72 
— 
— ■ ’ 
10-20 
9 9 99 
59-5 
2.88 
5-60 
c. 10 
10-20 
The conductivity figures 
are 
arranged in 
ascending 
series. 
It will be 
seen that the germination figures increase in the same direction, though with 
small irregularities. When 
one 
remembers 
the variation in 
germinative 
capacity among spores and the necessity of carrying out the measurements 
of germ-tube length rapidly, and therefore over a comparatively small 
number of spores (in this case 25 ), these irregularities are not surprising. 
In the following table the conductivity figures are grouped within 
certain limits and the corresponding amounts of germination averaged. 
In this table it will be seen that the irregularities have almost completely 
disappeared. 
Drop. Conductivity. Average length of germ tube. 
12 hrs. 
16 hrs. 
24 hrs. 
36 hrs. 
Distilled water 
0.8 
0-16 
0.22 
0-20 
0-46 
Drops on Cereus petal 
1-2 
0.22 
0*24 
0.38 
o-8o 
a a 
2-5 
0.76 
1^6 
2.67 
3*07 
a a 
5 -!° 
i -93 
2.85 
4-36 
5-14 
a a 
xo-20 
2-04 
2-64 
4.90 
7*36 
If if 
20-35 
2-73 
5.08 
c. 10 
10-20 
a a 
> 35 
2.88 
5.60 
c. 10 
10-20 
In a similar experiment the drops which had lain on Cereus petals 
were compared as regards both conductivity and germinative capacity side 
by side with dilutions of a turnip extract. The figures are contained in the 
following table : 
