in the Bromes and their Brown Rust . 275 
particles, which then run together, and the drop may then 
be held by capillary attraction to the now wetted surface. 
A method which promised to obviate some of the draw- 
backs referred to was that of placing minute swabs of cotton- 
wool or paper-pulp — scraped filter-paper fibres— saturated with 
spore-laden water on the leaves ; such swabs stick well and 
as they dry mark the spot infected : but although their 
presence does not hinder the germination of the spores, the 
method was not particularly successful, for in some cases 
the germ-tubes ran into the damp interspaces of the cotton- 
wool and there lost themselves, as it were. 
Returning now to the treatment of the seedlings. Having 
sown the spores, each pot was covered with a large inverted 
beaker lined with moist filter-paper, and placed in the west 
window. After 24-48 hours the beakers were removed, and 
the pots placed under very large bell-jars in zinc trays, and 
these bell-jars were usually removed on the third or fourth 
day, and the pots placed in the open. 
Of course differences in detail of procedure had to be 
introduced to meet exigencies of weather, and I availed my- 
self of the cellar or area in the hottest weather, and of tables 
and boxes in shade and half-shade in various positions in the 
garden. These details are given in the tabulated results. 
It is certain that these differences of temperature, illumina- 
tion, drought and wet, and so forth, affecting the transpiration, 
assimilation, &c., of the seedlings, also affect the period of 
germination, inoculation, and incubation, and difficulties in 
explaining various phases can be overcome only when this is 
understood. 
8. The Results of Infection. 
Successful inoculation is followed by a period of incuba- 
tion usually about a week to ten days in duration, during 
which period the hyphae are spreading in the intercellular 
spaces. 
We have seen that the germination of the spore is ruled by 
certain factors of which temperature is very important, 
