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Scientific Memoirs by
greatly that the whole leaf becomes extraordinarily deformed. When the veins
are attacked in their continuity, they curve while swelling very greatly with their
convexities usually downwards; but when the fungus attacks the branching point
of smaller veins, the most irregular contortions arise, some curving with their
convexities upwards, whilst others are twisted in the opposite direction. Some
idea may be gained of the extraordinary amount of hypertrophy produced by
the following actual measurements. The petiole of a leaf which was mon-
strously hypertrophied measured 12.7 c.m. in length and 2.2 c.m. in diameter
at its thickest part, and was curled round in a complete circle. When the
petioles are invaded their whole tissue is uniformly hypertrophied ; but when the
main stem is attacked (Fig. 1, Plate IV) the mycelium is strictly localised, and
the hypertrophied part appears in the form of an excrescence or well-defined
tumour. Such an excrescence, may or may not cause the stem to be bent towards
the opposite side. An extreme amount of such bending is shown in Fig. 1, Plate
IV. These tumours are often of great size ; one, by no means the largest that
could be found, measured 2.8 c.m. in length, 2 c.m. in breadth, and 1.2 c.m. in
depth. These extraordinarily hypertrophied parts contain an abundance of
nutritive starchy material, which the hill natives eat with relish, selecting them
just before the æcidia ripen. It is called by them khiri, a cucumber, on
account of the resemblance of its taste to that vegetable.
Generally, during the middle of June, the upper surfaces of the leaves of the
nettle present small circular patches of pale-yellow discoloration. Each patch
is usually much arched upwards with a corresponding concavity below. At
this time a leaf may have from one to five such patches. The upper surfaces
of these patches are densely studded with spermogonial papillæ, a few only
occurring on the lower surfaces. A fortnight or three weeks later the æcidial
fructification makes its appearance on the same patches, which have by this
time increased in area and thickness. Now, during the earlier part of July, large
thickenings and tumours occur plentifully ; but as soon as the rains have well set
in, these hypertrophied parts disappear, due to their rotting, mainly the result of
invasion by a white silky mould. But although at this season large hypertrophies
are not to be found, except in sheltered places, yet infection continues, for young
leaves even then show the earliest stages of attack by the parasite. Towards
the latter end of the rains, however, after the middle of August, the fungus dis-
appears entirely, and will not be found again until the following summer. The
nettle flowers towards the end of the rains (during the latter part of August),
and. I have in several other cases observed that when a flowering plant is
attacked by an æcidium before it flowers, the fungus disappears entirely just
before the flowers begin to open. For example, this is the case also with Æci-
dium Strobilanthis described in the preceding paper. The above seasonal cha-
racteristics of the fungus relate only to its appearance in Simla. At lower
elevations it appears earlier, for during May 1884, whilst at Rampur and other