a ee 
each containing a number of balls connected by 
strings; while the balls, though so minute as to 
be scarcely visible by the naked eye, are ascer- 
tained to be the receptacles or depositories of the 
spores. The veins of the leaves of the pear-tree are 
always observed to be the first seat of this fungus ; 
then the leaves become yellow and fall off; next 
the branches wither and die; and perhaps, in 
the course of two or three years, the whole of the 
orchard around an infected tree is attacked and 
destroyed. Leaves overpowered by the eecidium 
cancellatum are hideous objects. Their natural 
verdure has given place to a dark brown colour; 
their upper surface, within the embrowned por- 
tions, shows orange-coloured blotches; and their 
under surface, immediately beneath the blotches, 
shows softly wooded excrescences, projecting pale 
brown teat-like bags, more than a quarter of an 
inch in length, and closed at the mouth; and 
these bags or peridia are the depositories of the 
spores. Mr. Sowerby remarks, “ Aeidiwm can- 
cellatum has long been a troublesome parasite in 
many places, and has been the cause of much loss 
as to the trees which it attacks, as well as in 
expensive and useless attempts to get rid of it. I 
think, however, its very nature, like the dry rot, 
bespeaks an easy cure.” Yet he appears to be 
able to offer no better a prescription than one 
founded on the thecry that the fungus grows 
only in a certain degree of heat and moisture, 
and that this degree is capable of being observed 
and noted; and he would, therefore, be utterly 
baffled by the theory which seems now to have 
the general suffrage of naturalists, that the spores 
of zecidium, as well as of other genera of fungi, 
are disseminated in the soil, and taken up into 
the interior of plants by absorption through the 
spongioles,—and that, in consequence of this, 
when soil is once fouled with spores, no matter 
what may be the culture, plants are liable to be 
attacked with mildew, especially with that of the 
eecidia and the puccineze, in the exact proportion 
of their healthiness and vigour. 
The Axidium grossularie attacks gooseberry 
bushes, spreads with rapidity, and resists most 
efforts for its extinction —The Aeidium cornu- 
tum attacks the mountain ash, and makes simi- 
lar progress to that of the. Zeidium grossularie. 
—The fungus which attacks the sycamore maple 
tree, appears like a spot or little nodule of mi- 
nute oblong bodies, individually of purplish col- 
our, aggregately of blackish exterior, but yellow 
in the inside, and containing tubes filled with 
seeds.—The erdium quadrifidum attacks the 
Anemone coronaria renders its appearance pale 
and sickly, and generally prevents all or part of 
it from producing flowers. Spots of a light col- 
our on the under surface of the leaves, first in- 
dicate the presence of this fungus; the spots 
soon become small tuberculate membranaceous 
bodies, or peridia; and these peridia protrude 
themselves through the epidermis of the leaves, 
and, though at first closed, they afterwards open 
JECIDIUM. 
into four, five, or more broad, reflected segments, 
and permit the spores which they had enclosed 
to make their escape. The deidiwm leucosper- 
mum attacks the Anemone nemorosa and differs 
from the Aeidium quadrijidum in heing of smaller 
size and lighter colour, and in opening into a 
greater number of reflected segments.—The ci- 
dium fuscum also attacks the Anemone nemorosa ; 
and it grows on the under surface of the leaves, 
and gives them somewhat the appearance of fruc- | 
tifying ferns. 
The Acidium laceratum attacks the hawthorn, 
and has been known to destroy a large portion 
of a hawthorn hedge. A minute point, such as 
might be made by the puncture of an insect, is 
the first appearance of the fungus; but this 
gradually swells into a protuberance of compara- 
tively large size, covered with minute peridia, 
containing the spores of the plant. The protu- 
berances occur chiefly about the middle of the 
young shoots of the hawthorn, but sometimes 
toward the extremity of the young shoots, and 
frequently in the leaves; they vary in number 
on each young shoot from one to three or more; 
they generally have an oval shape, but are often 
singularly curled and distorted ; they vary in 
bulk from the size of a bean to that of a walnut ; 
they have sometimes a smooth but generally a 
brown shaggy exterior; they are covered with 
numerous and crowded orifices, so minute as to 
be visible only through a magnifying glass, and | 
each surrounded with many mimic leaves, and 
containing the spores of the fungus; and their 
interior is solid, and without any appearance of 
being inhabited by insects, yet of a less consistent | 
and more brittle character than the adjoining 
portions of the hawthorn’s shoot. An interest- 
ing paper of Mr. Don of Hull—to which we are 
indebted for most of these particulars respecting 
the Zeidium laceratwm, and which was published 
in the Memoirs of the Caledonian Horticultural 
Society, and republished in the ‘Quarterly Jour- 
nal of Agriculture’ and ‘Loudon’s Gardener’s 
Magazine’—states that, in 1812 and 1813, about 
100 yards of a young hawthorn hedge round the 
botanic garden of Hull, were reduced by this 
fungus to a dwarfish condition, and that every 
one of the mildewed shoots appeared to have 
died down to the lowest protuberance. 
The rapid, irrepressible, and devastating spread 
of the Alcidia is a phenomenon well worthy of 
investigation, and, as yet, very obscurely appre- 
hended. The leaves of plants, it has been thought 
by some persons, are affected with some loss of 
energy, become suitable soil for the feeding of 
fungi, and speedily receive some of the innumer- 
able spores which are supposed to be floating in 
the atmosphere. But both this hypothesis and 
most others which have been advanced, seem to 
be quite incompatible with the fact that the 
gecidia, as well as the genera allied to them, uni- 
formly develop themselves beneath the epidermis 
or within the leaf-veins of plants; and burst out- 
