Scientific Memoirs by .
under surfaces, and upon those of the other (B) upon their upper surfaces, and
they were then kept under a glass shade in my. laboratory. Unfortunately all the
leaves of (A) died early without any sign of infection. On the 17th May, three
of five leaves on one shoot of (B) and five of eight on the other shoot showed
distinct foci of infection with young spermogonia already developed. On the
2 1 st, of the ten leaves still remaining (three had withered and fallen off), all were
attacked, five showing single centres of infection, three with three centres each,
one with four centres, and one with five centres, of infection. The leaves
withered before any æcidia were formed.
Experiment IV. —Two young plants of Strobilanthes, (A) and (B), got from
nature, and which appeared to be quite free from any affection, were placed in
pots. On 11th May the leaves of these were inoculated with teleutospores
collected the previous day. The leaves of (A) borne on five shoots were inocu-
lated on the upper surfaces ; and those of (B), which had four shoots, were
inoculated on their under Surfaces. They were then kept for some days under a
glass shade in my laboratory. On the 4th May, discoloured spots were observed
on a few leaves of each, but fewer on (A) than on (B). On the 3rd June, after my
return from a short absence, (A) had 46 leaves, of which 42 presented distinct
signs of infection with numerous spermogonia, and a few æcidia ready to burst,
whilst (B) had 41 leaves, of which 30 were affected, but as yet without
æ c i d i a .
There was thus little difference displayed in the attack of the leaves from the
upper and from the lower surfaces those attacked from above were a little
more largely and more quickly affected than those attacked from below. Later
on, both plants produced an abundant crop of æcidia with well-developed æcido-
spores which germinated freely in growing cells, and some of which were used in
infecting Stipa as described in Experiment X.
Experiment V.—The same stock of teleutospores used in Experiment
IV were indiscriminately applied the same day to several leaves of a large plant I
had kept in a hot-house, and which had larger leaves than any I had yet experi-
mented with. This plant was potted during the previous autumn and, after ino-
culation, remained in the hot-house, where it grew luxuriantly. A large number
of these leaves became infected, and on 12th June I noted that several of the
affected areas showed the peculiar rosy colour below observed usually in nature,
and which had not been observed in my previous experiments. The course of
invasion in this case pursued a more natural course than in any of the above ex-
periments, which I attribute to the plant having been kept under more natural
conditions, to only a few of the many leaves it bore having been inoculated, and
to these having been inoculated at a more advanced stage of development, and
more nearly approaching the age at which leave's in nature are usually attack-
ed. Figure I represents one of these leaves drawn towards the end of June.
Experiment VI.—The terminal end of a small shoot containing four leaves
was cut off, and the cut end placed under water. The leaves were inoculated