io8 Brow 7i. — Studies hi the Physiology of Parasitism. VIII. 
Drop. 
Conductivity . 
Average length of germ tube. 
10 hrs. 20 hrs. 40 hrs. 
Distilled water (av. of 3) 
0-70 
°'44 
073 
1 -02 
From glass slides 
1. 19 
044 
083 
1-02 
From Cereus petals 
1-2 av. 1-50 
0-64 
I.24 
2-20 
99 99 
2-3 av. 2.15 
0.67 
r 74 
271 
9 9 99 
3-4 a v. 371 
1.22 
3-23 
5.28 
9 > 99 
4-3 av. 4.28 
1-67 
3- 2 7 
5-94 
9 > 99 
5-6 av. 5.60 
2-04 
6.08 
7-52 
Turnip extract 1/1 
73 -o 
0.64 
6.08 
weft 1 
» „ i /5 
61.6 
2.88 
> 10 
99 
>> >> i / 2 5 
38-8 
4*20 
> 10 
,, ,, 1/100 
16.8 
4-28 
> 10 
99 
„ „ 1/400 
6-22 
3-76 
> 10 
,, ,, 1/1,000 
3-28 
3-96 
7.48 
99 
,, ,, 1/4,000 
1-40 
376 
lost 
Wk gj 1 
,, ,, 1/20,000 
1. 1 4 
2- 80 
4-28 
5*48 
,, 1/100,000 
0.77 
1-64 
3.20 
5.28 
1 The compactness of the wefts was 
seen to be in order diminishing 
with diluti 
on. The amount 
of growth was obviously greatest in the full strength extract. 
It will be noted that the amount of germination on drops from Cereus 
petals is considerably less than that in turnip extract of the same con- 
ductivity. Similar dilutions of apple extract showed the same feature. 
This is no doubt to be ascribed to the fact that the turnip and apple 
extracts contain the bulk of the soluble cell contents, both those which are 
readily and those which are more slowly diffusible ; whereas the drops 
from Cereus petals contain a preponderating proportion of the more readily 
diffusible constituents such as salts. The presence of these would raise 
the conductivity of the drops, while the smaller proportion present of the 
more slowly diffusible carbohydrates, &c., would have the effect of 
making the fungal germination meagre. 
Incidentally it may be seen that, as the concentration of turnip extract 
increases, the amount of germination passes through a maximum. This is 
well shown in the figures for the germination after io hours. It is still 
shown to some extent after 20 hours, but has disappeared in 40 hours, 
when the amount of growth is greatest in the strongest extract. This 
feature is shown by other extracts and by other fungi than Botrytis. 
The correspondence between the conductivity and the germinative 
capacity of the drops from Cereus petals is again clearly shown in the above 
table. 
It will be noticed that the conductivity of drops laid on glass slides is 
greater than that of the original distilled water freshly taken from the stock 
bottle. A similar small increase in conductivity was also shown by drops 
laid on clean quartz slides and on glass slides maintained in a vacuum. The 
cause of this slight gain in conductivity was not clearly made out. It is 
probably due to a variety of causes, partly to solution of carbon dioxide 
from the air, partly to leaching of salts from the glass, and partly to 
accidental contamination with specks of dust. From the point of view of 
