Medical Officers of the Army of India.
in a pot, was kept uncovered in my laboratory ; but on the 19th it was protected
still further by being placed under a glass shade. On the 23rd April nine leaves
in all displayed in the same paling in spots or patches. In most cases each
leaf presented several paled areas, and minute, yellowish, differentiated points
could now readily be detected in several of these, which promised to develope
into mature spermogonia. The anticipation was fulfilled a few days later when
these points developed into minute pustules with pellucid summits, and micro-
scopical examination left no further doubt as to their being mature spermo-
gonia. On the 3rd May, several ripe æcidia were found in most invaded areas
with well-developed æcidiospores.
Experiment II.—On the 19th April, when in the course of my first experi-
ment it appeared probable that these teleutospores had produced a mycelium
in Strobilanthes, I inoculated all the leaves of five other branches which this
plant bore with the same stock of spores I had collected on 30th March, and part
of which I had used in Experiment I. The plant was then placed under a glass
shade and kept in my laboratory. On the 24th April, only two leaves appeared
to have become attacked with paling, bulging, and slight thickening, of the blade
tissues. Thinking that my spore material might have become injured in some
way by keeping, I re-inoculated all the leaves which remained unaffected with
freshly-collected spores on 25th April. The weather was now warmer and the
leaves were attacked more quickly ; for, on the 28th April, the leaves on the five
branches were in the following condition : On one branch five of ten leaves
were distinctly affected ; on the second, which had nine leaves, none were
affected ; on the third, three of four leaves were affected ; on the fourth, one of
four leaves was affected ; and on the fifth, two of six leaves were affected. The
usual course of development was run through in all cases, and during the second
week of May several infected areas produced ripe æcidia. The æcidiospores from
these germinated readily, one of which is represented in figure 10, after having
been twenty-four hours in water. As this plant was kept throughout the experi-
ment in my laboratory under a glass shade, there was no possibility of the in-
fection having occurred from accidental causes from without ; and, moreover,
throughout all my experiments, all nature acted as a control experiment, for I did
not meet with affected plants in nature this year until the 15th July, although
I watched constantly and carefully for its first appearance. But the artificial
conditions under which this plant was placed were evidently not favourable for
the complete and robust development of the fungus, as æcidial cups were not
produced on the affected areas so abundantly as they are in nature. The atmo-
sphere around it was probably too moist, and the light not sufficiently intense
to keep the host in full vigour.
Experiment III. —On 5th May, two small branches were cut off from
another plant kept in my verandah since the previous year, and the stems placed
in water. The leaves were young, fresh, and quite normal in appearance. Upon
the leaves of one (A) spores collected the same day were placed on their
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