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THE COTTAGE GARDENER AND COUNTRY GENTLEMAN’S COMPANION, September 22, 1857. 395 
condition, or so mixed with Cystopus candidus, that no correct 
conclusion could be formed as to the true affinities of the 
plant. Unger meanwhile had supposed that the white spots 
so common on the leaves of the common Celandine, Ground 
Ivy, and other plants, consisting of short moniliform erect 
threads, were the production figured by Greville, though 
without the slightest authority for such a supposition, and 
totally at variance with the Avhole account and figure given 
by the great Scottish cryptogamist. Matters were in this 
condition when the original specimen was kindly lent by Dr. 
Greville to the author of the present memoir; and though 
almost entirely destroyed, a morsel of the plant was in a 
sufficiently good condition to show that it had no near 
affinity with Uredo , that it had still less with the parasitic 
moulds, that at any rate it was produced beneath the surface 
of the leaf, and that the spores oozed out by reason of the 
contraction of the substance of the leaf upon the pulpy 
mass stored up beneath the cuticle. There was, indeed, 
some difficulty about the genus, but little as to its true 
affinities. In the spring of 1850 a single plant of Cauli¬ 
flower attracted my attention from its leprous aspect, which 
seemed somewhat different from that exhibited by other 
plants attacked by the common white rust ( Cystopus can¬ 
didus). On examination it was, to my great delight, clear 
that I had at last discovered the doubtful plant of Greville. 
The summer proved most unpropitious to the growth of 
Cauliflowers, few coming to perfection till late in the year, 
whatever the variety might be. Mine consisted of those 
distributed by the Horticultural Society, with the addition of 
the Walcheren , and neither my own garden nor those of my 
neighbours, who had merely the old variety commonly grown, 
exhibited a really good specimen; and the complaint pro¬ 
bably might have been made very generally, as an inspection 
of the specimens exposed for sale in Covent Garden during 
the summer, on more than one occasion, showed that at 
least for part of the season they were neither plentiful nor 
well formed. At any rate the crop was most miserable here, 
and at the end of June and the beginning of July, in a large 
garden where multitudes are grown for the supply of the 
neighbouring markets, almost every plant, amongst which 
there was scarcely one which had not run, was white with 
the same interesting fungus which I had observed earlier in 
the year at home. 
How far the condition of the crop might be due to any 
peculiarity of the season, or to the presence of the fungus, 
whose growth was favoured by the state of the atmosphere, 
it is impossible to say, though both in the case of the Cys¬ 
topus and the fungus under consideration, I have observed 
a tendency in the plants infested to produce a multitude of 
green bracts amongst the flowers, greatly impairiag the 
beauty, and consequently the market value, of the produce, 
even where tolerable heads are formed. 
The parasite forms, both upon the upper and under sur¬ 
face of the leaf, roundish often confluent patches, varying 
greatly in size, consisting of little white specks disposed 
more or less concentrically, those of the centre frequently 
becoming yellow, and at length fading away, in consequence 
of the partial decomposition of the leaf which they have 
affected, while the outer pustules spread from the circum¬ 
ference to the part yet remaining healthy. Occasionally they 
extend to the midrib, which is then rapidly destroyed. On 
close examination it is found that the fungus, each speck 
forming a distinct individual, is produced between the true 
cuticle and the cuticular cells. To ascertain this point re¬ 
quires rather delicate manipulation, but the fact is very clear 
in an extremely thin slice, provided the flaccid membrane 
has not unfortunately been turned aside by the edge of the 
lancet with which the section is made. The cuticular cells, 
however, are much confused and deranged by the growth of 
the parasite, which is developed principally at their expense, 
those of the succeeding layer being very little if at all 
affected. The mycelium is closely incorporated with the 
cuticular* cells, and appears simply grumous, without distinct 
structure: this, however, may be owing to its being so 
delicate as to be broken up under the knife; at any rate it 
does not appear to be filamentous. From the top of this 
mass, on the level of the tips of the cells, on which it 
grows, arise very short delicate sporophores, each of which 
is surmounted by an oblong, cylindric, often curved spore, 
three to five times as long as broad, and containing at ma¬ 
turity from two to three globose nuclei. It is highly pro¬ 
bable that each sporopliore produces in succession several 
spores, which are thus pushed forward, and in time fill the 
space between the true cuticle and the cuticular cells, 
thrusting the former out until it bursts. Partly owing to the 
successive development of the spores, which are mixed with 
a viscid fluid, and partly to the contraction of the leaf itself 
upon the pulpy mass, in dry weather or when exposed to the 
direct rays of the sun, the spores ooze out, kept in con¬ 
nection with each other by means of their attendant muci¬ 
lage, and drying as they are exposed to the air, form rude 
irregular short tendrils. These tendrils are in their turn 
softened again by moisture, and after a time fall down, 
forming a little pellicle upon the leaf, the edges of which 
are often curved up like a little boat or canoe, as observed 
originally by Dr. Greville. There is not the slightest trace 
of a perithecium, so that we have here one of the lowest 
possible forms of the group to which it belongs. The spores, 
it should be observed, are not truly trun¬ 
cate, as they appeared to Greville when 
examined by the old imperfect compound 
microscope, but rounded and obtuse. They 
do not arise from the division of a thread 
in the direction of the septa, in which 
case they might indeed be truly truncate, 
but from the development and expansion 
of a distinct cell produced at the tips of 
the sporophores. 
The question now arises, To what genus 
is the production to be assigned? Dr. 
Greville was undoubtedly correct in form¬ 
ing a new genus for its reception, for it 
could not be referred to any established at 
the time in which ho wrote. As said 
above, the genus was misunderstood by 
succeeding observers, and the name ap¬ 
plied to very different objects. A species 
on Ivy, clearly congeneric, was published 
by l)e Notaris, in his Micrvmycetes , 
under the name of Myxosporium para- 
doxum , the specific term being intended to 
denote the complete absence of perithe¬ 
cium. De Notaris appears, however, to 
have forgotten that Link had already pro¬ 
posed a genus Myxosporium , which is, in 
fact, synonymous with Ncemaspora, N. crocea 
being taken as its type to the exclusion 
of the similar Libertclla. A third species 
Fig. 1 .—Portion of a patch of Olaosporium concentricum, just after the spores have 
oozed out, magnified. 
Fig. 2.—Ditto where the irregular cirrhi have subsided from moisture, magnified. 
Fig. 3.—Section of a leaf, from a firm part destitute of lacunae, showing the fungus 
occupying the space which ought to be occupied by the subcuticular cells, highly 
magnified. 
Fig. 4.—Spores and sporophores, highly magnified. 
Fig. 5.—Spores, still more highly magnified, from a sketch by Mr. Broome, 
