in the Bromes and their Brown Rust . 269 
portance were overlooked. Nevertheless it seems worth while 
noting the positive results. 
The effects of different temperatures seem to be much 
more definite and important. 
As regards methods there is little tt> remark beyond what 
is told in Table X. The simplest results are those in watch- 
glasses of water, on the surface of which the spores were 
sown and the laboratory temperatures noted. In those cases 
where a definite temperature is given, however, the watch- 
glass was placed in the incubator. 
More accurate results are of course attainable in the cells ; 
i. e. the spores were in hanging drops in culture-cells in the 
heated microscope culture-box, and in these cases the tempera- 
tures, regulated with thermostat, &c ., are those of the drop 
itself and its surrounding atmosphere. 
In those cases where the word ‘heated 5 is added, it is to be 
understood that the temperature of the culture-box was slowly 
raised accurately to the range given. 
It is evident from the experiments (see Table X) that the 
spores, Uredospores, of this fungus germinate best at or near 
20 0 C, while the maximum is not far from 26-27-5° C, and 
the minimum about 10-12° C. 
It is somewhat surprising that such apparently delicate 
spores will withstand 10 minutes 5 freezing, but there can be no 
doubt of the fact. The watch-glass, with spores in water, was 
placed in an iced chamber, in a glass vessel surrounded by 
a freezing mixture, and the temperature, recorded by a small 
and delicate thermometer, went to —5° C, the mass freezing to 
a solid block of ice. A piece of this was chipped off and 
placed in a clean watch-glass at 20° C, with the result given 
in the Table. The spores germinated in less than ji hours. 
The rest of the frozen spores, kept frozen for 4-5 hours, could 
not be resuscitated. None of the spores heated to tempera- 
tures above 30° C could be resuscitated, and even 27-5° C was 
found to be a trying temperature in many cases. 
It seemed desirable in view of certain eventualities referred to 
in section 16 to test the possibility of the leaf containing some 
