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Scientific Memoirs by
on Smilax without any result, and secondly, because even in nature, although
the teleutospores are widely and plentifully distributed over the Simla region, the
aecidial form is found only in certain few localities, where only, I presume, the
special conditions necessary for attack exist (these localities were moist, densely
wooded, and therefore very shaded). The resemblance of the teleutospores to those
of Gymnosporangium induced me also to make many attempts to reproduce an
Aecidium (Roestelia) on Pyrus variolosa, Wall., which in certain years is very
common in Simla, but without success. This Roestelia is the only representative
of the genus in Simla, and there can, I think, be no doubt that it is caused by the
only Gymnosporangium in Simla, one on Cupressus torulosa, Don. I have, how-
e v e r , e l s e wh e r e 1 s h o wn t h a t , a l t h o u g h t h e s e l a s t t wo f u n g i mu s t b e r e l a t e d , I c o u l d
never demonstrate it by experiment. And this case shows very forcibly how easily
inoculation experiments may fail, because it is scarcely conceivable that this only
Gymnosporangium, which occurs in Simla, is not related to the only Roestelia we
have. There is also this parallelism between the Pyrus and Smilax Aecidia that
both are relatively rare in comparison with the largely distributed and readily
germinating teleutospores, and here, too, I think my inoculations have not suc-
ceeded, because some special unknown condition, comparatively rare even in
nature, must be present before attack by the teleutospores can take place.
I was even more unsuccessful in attempting to produce the uredo-form by
sowing with aecidiospores, for all my experiments in this direction were fruitless.
The fact, however, that in nature, in October, the leaves which bore aecidia were
also invariably attacked by the uredo-producing mycelium lends strong support
to the view that this was the result of infection by the aecidiospores produced
on the same leaf.
The total result therefore is that, although unimpeachable evidence does not
exist to connect the two forms of fungus with one another, such a connec-
tion is rendered in the highest degree probable by a consideration of the facts
above set forth.
In my introductory remarks I noted that I felt doubtful whether the phase
I have described as aecidial were really so or not. I doubted because (1) the
aecidia were unlike other aecidia in opening by a pore, (2) because the aecidio-
spores were not formed in rows as usual, and (3) because the aecidiospores are
morphologically scarcely distinguishable from the uredospores. But, as I have
said, I have now no longer any hesitation on this point, because the character
and properties of the mycelium producing the aecidia are very different from
those of the uredo-producing mycelium, and because the acidia are always
accompanied by spermogonia, and the mycelium which produces these organs
never produces teleutospores. The reason why the aecidiospores are not formed
in rows may, I think, be due to the aecidia not opening widely enough to
admit of this. As soon as a few aecidiospores are formed within the limited
capacity of the aecidium there is no room for others until some are extruded.
1 Journal of t he Asi at i c Soci et y of Bengal , Vol . LVI, Part II, No. 3, 1887.