THE COTTAGE GARDENER AND COUNTRY GENTLEMAN, January 12, 1858. 
mycelium of the parasitic Fungi which attend or produce 
mildew, and I was glad of the opportunity of examining the 
present parasite with kirn. The specimens were somewhat 
decayed, in consequence of having been some time on the road, 
and their odour was extremely disgusting. On making a 
section through the plant, every part of it was found to be 
more or less decomposed, and filled with white mycelium, 
which was occasionally greenish from the juices of the matrix; 
amongst which appeared the Sclerotium , in various stages of 
growth, distinguished in the younger specimens by its com¬ 
pact substance, and in the older by the dark blackish cuticle. 
It was a matter of importance to ascertain, if possible, what 
was the nature of these globular bodies ; and the manipulation 
applied by Mr. Hoffman, to the observation of mycelium in 
other cases appeared likely to lead to some positive result. 
Leveille has, in his interesting memoir on the genus Scle¬ 
rotium, combated the pretensions of the substances comprised 
under that name, to occupy a place amongst autonomous 
Fungi; and though his observations are as conclusive as the 
nature of the case would admit, without an experiment like 
tliat now recorded, which alone could furnish the means of 
seeing the actual development of the Fungi from the mycelium 
of which they are so many anamorphoses, they require some 
direct confirmation, which does not, however, at all detract 
from their own original merit. It became, therefore, a matter 
of interest to embrace the opportunity now offered of following 
up the point. 
It is well known that it is possible to watch many mucedines 
from the first germination of the spore to the complete develop¬ 
ment of the fructification, by simply placing the reproductive 
bodies in a drop of water on a slip of glass, covering it with a 
piece of microscopic glass, and luting the edges with wax to 
prevent evaporation. The mycelium is developed in the 
water, while the fertile branches make their way into the sur¬ 
rounding stratum of air, and bear fruit. It was determined 
to subject a portion of the mycelium from the tissues of the 
diseased Onion, and a portion of the Sclerotium , to this process. 
In one slip of glass our success was complete; in others more 
or less perfect. A single observation, if possible, should not 
be relied upon. An extremely thin slice from the stem was 
taken, so thin as to enable us to distinguish easily the several 
parts of which the object w r as composed. The cells and 
vessels of the matrix were well defined; and the mycelium 
connected evidently with the sclerotioid granules which were 
separated from each other by veins of flocci, very much in the 
same way in which sporangia of certain Fungi are combined. 
It was easy also to recognise the structure of the Sclerotium 
as well externally as internally. The inner tissue was found 
to be not compactly cellular like that of Sclerotium durum , 
complanatum , &c., but filamentous, as in Sclerotium Boleto- 
•rum , Corda, consisting of closely interwoven branched 
threads, resembling, on a small scale, the tissues of the seed- 
pods of Fucus vesiculosus. This structure, it is obvious, made 
it more easy to trace the continuation of the mycelium from 
the tissue of the Sclerotium. 
After the expiration of a few hours, the slices began to 
assume a different appearance, from the elongation of the 
mycelium, which was protruded on all sides, and was branched 
and flexuous. Some portions were repeatedly articulated ; 
others either entirely without articulations, or with merely 
one or two scattered dissepiments. As long as the mycelium 
was confined to the drop of water, there was no appearance of 
fructification; and even the tips of the filaments were scarcely 
incrassated. There was not, then, the slightest intimation to 
what genus of Fungi it belonged; but no sooner had it 
penetrated through the globule of water into the surrounding 
air, than a marked change took place. The tips of the short 
lateral branches became incrassated, and at length globose, 
and contained a grumous mass, which soon manifested definite 
spores ; shortly after which the vesicle burst, and the oblong 
elliptic spores were exposed, still adhering to the tips of the 
threads—characters belonging manifestly to the genus Mucor. 
The sporangia, however, were of extreme minuteness, not ex¬ 
ceeding in diameter that of the individual cells of the Onion 
stem on which they grew. The appearance, indeed, was that 
of an Acremonium; but the globular heads of that genus have 
not been observed to be sporangia, and were such indeed 
the case, there would be no character by which to separate it 
from Mucor , except the comparative minuteness. No colu¬ 
mella was observed; but it is possible that in so very minute 
a body, examined in air without the aid of a liquid medium, 
which every microscopic observer knows to be of the first im¬ 
portance, it might have been overlooked. One or two very ! 
minute species have been observed by authors as Mucor sue- ! 
cosus; by myself, on inspissated sap oozing from the stem of 
Aucuba Japonic a; Mucor Fimbria, by Nees ; and Mucor im- 
perceptibilis, by Schrank : but the two former are far larger j 
productions ; and the nature of the latter, which grows under 
water, is extremely uncertain; and, as Nees von Esenbeck, 
who has reproduced Schrank’s figures, says expressly, requires 
fresh observations. There was some peculiar arrangement of 
die spores within the vesicles; but, unfortunately, the most 
perfect sketch of the appearance has been mislaid; and, indeed, 
ke different stages of growth succeeded each other so rapidly, 
that it was not sufficiently observed. This was the more to 
be regretted, as it might have thrown some light upon peculiar 
arrangements mother moulds, especially in Stilbum piliforme, 
Corda, where the spores are disposed somewhat in the fashion 
of the cells in the globules of Char a and JSitella. It must be 
remembered that there is good reason to believe with Corda, 
that each sterigma has the power of producing a succession of 
spores, which, as they are thrust off by the growth of the 
new spore, are deposited within the vesicle according to me¬ 
chanical laws. The specimen furnished no information as to 
the development of the fallen spores. 
It appears, then, that the mildew in the instance under con¬ 
sideration was due to the presence of a most minute micro¬ 
scopic mould, bearing about the same relation in point of size 
to the larger species, that Salix herbacea does to well-grown 
trees of Salix alba. The mould was in every part of the plant 
concentrated at numberless points into the form of a Sclero¬ 
tium , thus confirming directly the views of Leveille respecting 
that supposed genus. It was observed above, that no lorm of 
fructification was visible in the portion of the mycelium which 
was situated within the drop of water. That moulds when 
growing hi water not only present great differences as to their 
mycelium, but even as to fructification, appears from the 
various observations which refer such states to Algae, or to 
distinct genera of mucedines and mucorini. Adilya prolifer a, 
respecting which Unger has made such curious observations, 
is probably a mere anamorphosis of some mould; or, if not so, 
it is at least an aquatic species, and so far anomalous, though 
scarcely more so than the Algerian Sphceria Bosidonia ;, 
Montague and Durieu, which grows on the shoots of Bosidonia 
when yet remaining on their marine bed, and constantly 
covered by the sea, and is a very highly-developed species. 
A curious observation was made in the autumn of 1846, by 
Mr. Hoffman, on a mycelium, with which the interior of a 
decaying Pear was impregnated. It should be mentioned first 
that during that autumn, the leaves of many Apple and Pear 
trees at Margate were covered with a white flocculent Fungus, 
which was, however, never seen in fruit. All the fruit of 
these particular trees rotted ; and though no Fungus appeared 
externally, the cells of the fruit exhibited very clearly a jointed 
mycelium. An extremely minute portion of this, cleared as 
much as possible from the cellular substance of the matrix, 
was subjected to precisely the same treatment as that observed 
in the examination of the Onion mildew. It shortly began to 
grow and spread in all directions ; but so long as it was con¬ 
fined to the fluid, no normal fructification appeared ; the 
articulations of the threads, however, contained oblong-elliptic 
grains, which were soon dispersed in the fluid, after the fashion 
of the reproductive bodies in Bryopsis and some Conferva;. 
They possessed at first a slight molecular motion, which soon 
subsided ; and when they became stationary they germinated, 
and gave rise to jointed threads, similar to those of the parent 
mycelium. As soon, however, as the flocci penetrated into 
the surrounding air, a very different sort of fructification ap¬ 
peared, by which the mould was easily recognised as Beni- 
cillium candidum, Grev. The true spores were of the same 
form and size as those which had been developed within the 
threads in water ; and it should be observed that no external 
fruit had appeared when the grains of the joints were first 
dispersed, or even till after they had germinated. Precisely 
the same results were exhibited in a second experiment. It 
was found afterwards that, even in situ, as might be expected 
from the abundant moisture of the decayed fruit, the repro¬ 
ductive granules were produced within the threads and dis- 
