294 Brown . — Studies in the Physiology of Parasitism. IX. 
suitable objects for this work, similar results were also obtained with the 
spores of other fungi, as is shown in Table VI. 
Fungus. 
Table VI. 
With blotting-paper. 
Without blotting-pape • 
Control. 
Apple. 
Control. 
A pple. 
Eolrytis cinerea 
B. parasitica 
0-0 + 
3 - 5 2 
1.38 
4.12 
0.44 
i»o6 
1. 5 2 
1. 14 
Fusarium sp. 
0-00 
2.16 
2.00 
2-04 
In the case of the other fungi tested in this experiment, measurements 
were not taken, but the following is a description of the results : 
Penicillimn glaucunr. results follow the same lines as with Botrytis 
cinerea , i. e. apple without B.P. > apple with B.P., > control without B.P., 
> control with B.P. 
Colletotrichum Lindemuthianum : a small amount of germination in 
the control without blotting-paper : none at all in any of the others. 
Monilia fructigena : with young spores the amount of germination in 
all cases was so great that measurement was impracticable : with older 
spores the amount of individual variation in germinative capacity is 
very great. This fungus appears to be very unsuited to work of this 
description. 
The results with B. parasitica require further description. The figures 
in the above table give a very inadequate representation of the picture 
presented. All the germinations in presence of apple show stout germ- 
tubes, whereas the latter are very slender in the controls. The best 
illustrations of this effect have been met with in the case of this fungus. 
With Fusarium spores, a distinct stimulation by apple was only seen in the 
presence of blotting-paper. This fungus is also not very convenient for 
measurement, as it is generally not easy to decide where the germ-tube 
begins and the spore ends. The result with Colletotrichum is noteworthy 
as indicating the opposite response to the presence of apple tissue. 
It is interesting also to note that with the exception of Monilia (for 
which no data were obtained) all the fungi tested reacted in the usual way 
to the presence of blotting-paper. 
The effect of plant distillates and of various chemical substances was 
also tested. 
Leaves of Ruta and of Pelargonium were placed in water in a retort 
and subjected to distillation. The distillates were then tested either by 
adding one drop of each to one drop of a spore suspension or by placing 
filter-paper wetted with the distillates in the Petri dishes. The control 
series had water in place of the distillate. The amount of germination in 
the various distillate preparations varied from four to ten times that in the 
controls. There is no doubt, therefore, as to the effects produced by the 
plant tissues being due to volatile substances arising from the latter. 
