Fungi at various Temperatures , &c. 263 
suspension ; this effect is most strikingly shown in the case of lower 
concentrations of nutrient. 
In the following tables (I— III) the nutrient employed was a turnip 
extract obtained by extracting the juice of turnips boiled without any 
addition of water. This full-strength extract is denoted by T.E., and the 
various dilutions with water as T.E./10, & c. 
The different densities of spore suspension are denoted by m, m/10, 
m/100, where m denotes a suspension containing o-i c.c. of wet spores in 
10 c.c. liquid. In order to obtain these suspensions, spores were washed 
from a plate culture of Botrytis after the manner described in an earlier 
paper 1 and freed from mycelium by filtering through muslin. The spore 
suspension was then centrifugalized about six times in changes of water in 
order to complete washing, then finally centrifugalized in a graduated tube 
and the volume of spores determined. This being known, the various 
dilutions in the various concentrations of nutrient could be made up. 
The germination tests were carried out as follows : Drops of the 
various suspensions were placed on clean glass slides, the latter placed on 
a rack in a moist container, and the required atmospheric conditions set up 
as already described. 
These tests were carried out at ordinary laboratory temperature 
(15-18°), the various containers being placed side by side, so that they 
were under similar temperature conditions throughout. From the method 
of preparing the spore suspensions complete absence of contamination could 
not be guaranteed, but as the tests were of short duration, any accidental 
'slight contamination was of no importance. 
Table I. 
Botrytis cinerea. 
Percentage of Germinated Spores after 20 Hours' Germination (based 
on at least 100 counts in each case). 
Spore 
Density. 
I 
Nutrient. 
Air. 
10 % C 0 2 . 
20% C 0 2 . 
30 % co 2 . 
[H 2 o 
37 
5 
0 
0 
m/100 J 
1 T.E./io,ooo 
72 
47 
0 
0 
1 T.E./i,ooo 
90-100 
75 
9 
0 
1 
[ T.E./100 
90-100 
74 
25 
0 
1 
(H 2 0 
0 
0 
0 
0 
m/10 -j 
| T.E./io,ooo 
1 T.E./i,ooo 
3 
5 i 
0 
25 
0 
2 
0 
0 
1 
[T.E./100 
80 
63 
18 
0 
j 
(H 2 0 
0 
0 
0 
0 
1 
T.E./io,ooo 
0 
0 
0 
0 
m •} 
T.E./i,ooo 
0 
0 
0 
0 
] 
T.E./100 
36 
23 
0 
0 
I 
(T.E /io 
84 
64 
8 
0 
Table II gives the average length of germ-tube in the same experiment, 
this quantity being determined by measuring by means of a micrometer the 
lengths of all the germ-tubes shown by the counted spores, and dividing 
1 W. Brown: Ann. Bot,, xxix. 3T9, 1915. 
U 
