fungi, living upon and at the expense of decay, appropriating the
changed elements of previous vegetable life to the support of a new
generation, and hastening disintegration and assimilation with the
soil. No one can have observed the mycelium of fungi at work on old
stumps, twigs, and decayed wood, without being struck with the
rapidity and certainty with which disintegration is being carried on.
The gardener casts on one side, in a pile as rubbish, twigs and
cuttings from his trees, which are useless to him, but which have
all derived much from the soil on which they flourished. Shortly
fungi make their appearance in species almost innumerable, sending
their subtle threads of mycelium deep into the tissues of the
woody substance, and the whole mass teems with new life. In this
metamorphosis as the fungi flourish so the twigs decay, for the new
life is supported at the expense of the old, and together the
destroyers and their victims return as useful constituents to the
soil from whence they were derived, and form fresh pabulum for a
succeeding season of green leaves and sweet flowers. In woods and
forests we can even more readily appreciate the good offices of
fungi in accelerating the decay of fallen leaves and twigs which
surround the base of the parent trees. In such places Nature is left
absolutely to her own resources, and what man would accomplish in
his carefully attended gardens and shrubberies must here be done
without his aid. What we call decay is merely change; change of
form, change of relationship, change of composition; and all these
changes are effected by various combined agencies--water, air,
light, heat, these furnishing new and suitable conditions for the
development of a new race of vegetables. These, by their vigorous
growth, continue what water and oxygen, stimulated by light and
heat, had begun, and as they flourish for a brief season on the fallen
glories of the past summer, make preparation for the coming spring.
Unfortunately this destructive power of fungi over vegetable tissues
is too often exemplified in a manner which man does not approve. The
dry rot is a name which has been given to the ravages of more than one
species of fungus which flourishes at the expense of the timber it
destroys. One of these forms of dry rot fungus is _Merulius
lacrymans_, which is sometimes spoken of as if it were the only one,
though perhaps the most destructive in houses. Another is _Polyporus
hybridus_, which attacks oak-built vessels;[X] and these are not the
only ones which are capable of mischief. It appears that the dry rot
fungus acts indirectly on the wood, whose cells are saturated with its
juice, and in consequence lose their lignine and cellulose, though
their walls suffer no corrosion. The different forms of decay in wood
are accompanied by fungi, which either completely destroy the tissue,
or alter its nature so much by the abstraction of the cellulose and
lignine, that it becomes loose and friable. Thus fungi induce the
rapid destruction of decaying wood. These are the conclusions
determined by Schacht, in his memoir on the subject.[Y]
We may allude, in passing, to another phase of destructiveness in the
mycelium of fungi, which traverse the soil and interfere most
injuriously with the growth of shrubs and trees. The reader of
journals devoted to horticulture will not fail to notice the constant
appeals for advice to stop the work of fungi in the soil, which
sometimes threatens vines, at others conifers, and at others
rhododendrons. Dead leaves, and other vegetable substances, not
thoroughly and completely decayed, are almost sure to introduce this
unwelcome element.
Living plants suffer considerably from the predations of parasitic
species, and foremost amongst these in importance are those which
attack the cereals. The corn mildew and its accompanying rust are
cosmopolitan, as far as we know, wherever corn is cultivated, whether
in Australia or on the slopes of the Himalayas. The same may also be
said of smut, for _Ustilago_ is as common in Asia and America as in
Europe. We have seen it on numerous grasses as well as on barley from
the Punjab, and a species different from _Ustilago maydis_ on the male
florets of maize from the same locality. In addition to this, we learn
that in 1870 one form made its appearance on rice. It was described as
constituting in some of the infested grains a whitish, gummy,
interlaced, ill-defined, thread-like mycelium, growing at the expense
of the tissues of the affected organs, and at last becoming converted
into a more or less coherent mass of spores, of a dirty green colour,
on the exterior of the deformed grains. Beneath the outer coating the
aggregated spores are of a bright orange red; the central portion has
a vesicular appearance, and is white in colour.[Z] It is difficult to
determine from the description what this so-called _Ustilago_ may be,
which was said to have affected a considerable portion of the standing
rice crop in the vicinity of Diamond Harbour.
Bunt is another pest (_Tilletia caries_) which occupies the whole
farinaceous portion of the grains of wheat. Since dressing the seed
wheat has been so widely adopted in this country, this pest has been
of comparatively little trouble. Sorghum and the small millets, in
countries where these are cultivated for food, are liable to attacks
from allied parasites. Ergot attacks wheat and rice as well as rye,
but not to such an extent as to have any important influence upon the
crop. Two or three other species of fungi are sometimes locally
troublesome, as _Dilophospora graminis_, and _Septoria nodorum_ on
wheat, but not to any considerable extent. In countries where maize is
extensively grown it has not only its own species of mildew
(_Puccinia_), but also one of the most enormous and destructive
species of _Ustilago_.
A singular parasite on grasses was found by Cesati in Italy, in 1850,
infesting the glumes of _Andropogon_.[a] It received the name of
_Cerebella Andropogonis_, but it never appears to have increased and
spread to such an extent as was at first feared.
Even more destructive than any of these is the potato disease[b]
(_Peronospora infestans_), which is, unfortunately, too well known to
need description. This disease was at one time attributed to various
causes, but long since its ascertained source has been acknowledged to
be a species of white mould, which also attacks tomatoes, but less
vigorously. De Bary has given considerable attention to this disease,
and his opinions are clearly detailed in his memoir on _Peronospora_,
as well as in his special pamphlet on the potato disease.[c] One sees
the cause of the epidemic, he says, in the diseased state of the
potato itself, produced either accidentally by unfavourable conditions
of soil and atmosphere, or by a depravation that the plant has
experienced in its culture. According to these opinions, the
vegetation of the parasite would be purely accidental, the disease
would be independent of it, the parasite would be able frequently even
to spare the diseased organs. Others see in the vegetation of the
_Peronospora_ the immediate or indirect cause of the various symptoms
of the disease; either that the parasite invades the stalks of the
potato, and in destroying them, or, so to speak, in poisoning them,
determines a diseased state of the tubercles, or that it introduces
itself into all the organs of the plant, and that its vegetation is
the immediate cause of all the symptoms of the disease that one meets
with in any organ whatever. His observations rigorously proved that
the opinions of the latter were those only which were well founded.
All the alterations seen on examining spontaneous individuals are
found when the _Peronospora_ is sown in a nourishing plant. The most
scrupulous examination demonstrates the most perfect identity between
the cultivated and spontaneous individuals as much in the organization
of the parasite as in the alteration of the plant that nourishes it.
In the experiments that he had made he affirms that he never observed
an individual or unhealthy predisposition of the nourishing plant. It
appeared to him, on the contrary, that the more the plant was healthy,
the more the mould prospered.
We cannot follow him through all the details of the growth and
development of the disease, or of his experiments on this and allied
species, which resulted in the affirmation that the mould immediately
determines the disease of the tubercles as well as that of the leaves,
and that the vegetation of the _Peronospora_ alone determines the
redoubtable epidemic to which the potato is exposed.[d] We believe
that this same observer is still engaged in a series of observations,
with the view, if possible, of suggesting some remedy or mitigation of
the disease.
Dr. Hassall pointed out, many years since, the action of fungous
mycelium, when coming in contact with cellular tissue, of inducing
decomposition, a fact which has been fully confirmed by Berkeley.
Unfortunately there are other species of the same genus of moulds which
are very destructive to garden produce. _Peronospora gangliformis_, B.,
attacks lettuces, and is but too common and injurious. _Peronospora
effusa_, Grev., is found on spinach and allied plants. _Peronospora
Schleideniana_, D. By., is in some years very common and destructive
to young onions, and field crops of lucerne are very liable to attack
from _Peronospora trifoliorum_, D. By.
The vine crops are liable to be seriously affected by a species of
mould, which is but the conidia form of a species of _Erysiphe_. This
mould, known under the name of _Oidium Tuckeri_, B., attacks the vines
in hothouses in this country, but on the Continent the vineyards often
suffer severely[e] from its depredations; unfortunately, not the only
pest to which the vine is subject, for an insect threatens to be even
more destructive.
Hop gardens suffer severely, in some years, from a similar disease; in
this instance the mature or ultimate form is perfected. The hop mildew
is _Sphærotheca Castagnei_, Lév., which first appears as whitish
mouldy blotches on the leaves, soon becoming discoloured, and
developing the black receptacles on either surface of the leaf. These
may be regarded as the cardinal diseases of fungoid origin to which
useful plants are subject in this country.
Amongst those of less importance, but still troublesome enough to
secure the anathemas of cultivators, may be mentioned _Puccinia Apii_,
Ca., often successful in spoiling beds of celery by attacking the
leaves; _Cystopus candidus_, Lév., and _Glæosporium concentricum_,
Grev., destructive to cabbages and other cruciferous plants;
_Trichobasis Fabæ_, Lév., unsparing when once established on beans;
_Erysiphe Martii_, Lév., in some seasons a great nuisance to the crop
of peas.
Fruit trees do not wholly escape, for _Roestelia cancellata_, Tul.,
attacks the leaves of the pear. _Puccinia prunorum_ affects the leaves
of almost all the varieties of plum. Blisters caused by _Ascomyces
deformans_, B., contort the leaves of peaches, as _Ascomyces
bullatus_, B., does those of the pear, and _Ascomyces juglandis_, B.,
those of the walnut. Happily we do not at present suffer from
_Ascomyces pruni_, Fchl., which, on the Continent, attacks young
plum-fruits, causing them to shrivel and fall. During the past year
pear-blossoms have suffered from what seems to be a form of
_Helminthosporium pyrorum_, and the branches are sometimes infected
with _Capnodium elongatum_; but orchards in the United States have a
worse foe in the "black knot,"[f] which causes gouty swellings in the
branches, and is caused by the _Sphæria morbosa_ of Schweinitz.
Cotton plants in India[g] were described by Dr. Shortt as subject to
the attacks of a kind of mildew, which from the description appeared
to be a species of _Erysiphe_, but on receiving specimens from India
for examination, we found it to be one of those diseased conditions of
tissue formerly classed with fungi under the name of _Erineum_; and a
species of Torula attacks cotton pods after they are ripe. Tea leaves
in plantations in Cachar have been said to suffer from some sort of
blight, but in all that we have seen insects appear to be the
depredators, although on the decaying leaves _Hendersonia theicola_,
Cooke, establishes itself.[h] The coffee plantations of Ceylon suffer
from the depredations of _Hemiliea vastatrix_, as well as from
insects.[i] Other useful plants have also their enemies in parasitic
fungi.
Olive-trees in the south of Europe suffer from the attacks of a
species of _Antennaria_, as do also orange and lemon trees from a
_Capnodium_, which covers the foliage as if with a coating of soot. In
fact most useful plants appear to have some enemy to contend with, and
it is fortunate, not only for the plant, but its cultivators, if this
enemy is less exacting than is the case with the potato, the vine, and
the hop.
Forestry in Britain is an insignificant interest compared to what
it is in some parts of Europe, in the United States, and in our
Indian possessions. In these latter places it becomes a matter of
importance to inquire what influence fungi exert on forest trees.
It may, however, be predicated that the injury caused by fungi is far
outstripped by insects, and that there are not many fungi which
become pests in such situations. Coniferous trees may be infested
with the species of _Peridermium_, which are undoubtedly injurious,
_Peridermium elatinum_, Lk., distorting and disfiguring the silver
fir, as _Peridermium Thomsoni_, B.,[j] does those of _Abies
Smithiana_ in the Himalayas. This species occurred at an elevation of
8,000 feet. The leaves become reduced in length one-half, curved,
and sprinkled, sometimes in double rows, with the large sori of
this species, which gives the tree a strange appearance, and at
length proves fatal, from the immense diversion of nutriment requisite
to support a parasite so large and multitudinous. The dried specimens
have a sweet scent resembling violets. In Northern Europe _Cæoma
pinitorquum_, D. By., seems to be plentiful and destructive. All
species of juniper, both in Europe and the United States, are
liable to be attacked and distorted by species of _Podisoma_[k] and
_Gymnosporangium_. _Antennaria pinophila_, Fr., is undoubtedly
injurious, as also are other species of _Antennaria_, which probably
attain their more complete development in _Capnodium_, of which
_Capnodium Citri_ is troublesome to orange-trees in the south of
Europe, and other species to other trees. How far birch-trees are
injured by _Dothidea betulina_, Fr., or _Melampsora betulina_, Lév.,
or poplars and aspens by _Melampsora populina_, Lév., and _Melampsora
tremulæ_, Lév., we cannot say. The species of _Lecythea_ found on
willow leaves have decidedly a prejudicial effect on the growth of
the affected plant.
Floriculture has to contend with many fungoid enemies, which sometimes
commit great ravages amongst the choicest flowers. Roses have to
contend against the two forms of _Phragmidium mucronatum_ as well as
_Asteroma Rosæ_. Still more disastrous is a species of _Erysiphei_,
which at first appears like a dense white mould. This is named
_Sphærotheca pannosa_. Nor is this all, for _Peronospora sparsa_, when
it attacks roses in conservatories, is merciless in its exactions.[l]
Sometimes violets will be distorted and spoiled by _Urocystis Violæ_.
The garden anemone is freely attacked by _Æcidium quadrifidum_.
Orchids are liable to spot from fungi on the leaves, and recently the
whole of the choicest hollyhocks have been threatened with destruction
by a merciless foe in _Puccinia malvacearum_. This fungus was first
made known to the world as an inhabitant of South America many years
ago. It seems next to have come into notoriety in the Australian
colonies. Then two or three years ago we hear of it for the first time
on the continent of Europe, and last year for the first time in any
threatening form in our own islands. During the present year its
ravages are spreading, until all admirers of hollyhocks begin to feel
alarm lest it should entirely exterminate the hollyhock from
cultivation. It is common on wild mallows, and cotton cultivators must
be on the alert, for there is a probability that other malvaceous
plants may suffer.
A writer in the "Gardener's Chronicle" has proposed a remedy for the
hollyhock disease, which he hopes will prove effectual. He says, "This
terrible disease has now, for twelve months, threatened the complete
annihilation of the glorious family of hollyhock, and to baffle all
the antidotes that the ingenuity of man could suggest, so rapidly does
it spread and accomplish its deadly work. Of this I have had very sad
evidence, as last year at this time I had charge of, if not the
largest, one of the largest and finest collections of hollyhocks
anywhere in cultivation, which had been under my special care for
eleven years, and up to within a month of my resigning that position I
had observed nothing uncommon amongst them; but before taking my final
leave of them I had to witness the melancholy spectacle of bed after
bed being smitten down, and amongst them many splendid seedlings,
which had cost me years of patience and anxiety to produce. And
again, upon taking a share and the management of this business,
another infected collection fell to my lot, so that I have been doing
earnest battle with this disease since its first appearance amongst
us, and I must confess that, up to a very short time back, I had come
in for a great deal the worst of the fight, although I had made use of
every agent I could imagine as being likely to aid me, and all that
many competent friends could suggest. But lately I was reminded of
Condy's patent fluid, diluted with water, and at once procured a
bottle of the green quality, and applied it in the proportion of a
large tablespoonful to one quart of water, and upon examining the
plants dressed, twelve hours afterwards, was delighted to find it had
effectually destroyed the disease (which is easily discernible, as
when it is living and thriving it is of a light grey colour, but when
killed it becomes of a rusty black). Further to test the power at
which the plant was capable of bearing the antidote without injury, I
used it double the strength. This dose was instant death to the pest,
leaving no trace of any injury to the foliage. As to its application,
I advocate sponging in all dressings of this description. Syringing is
a very ready means, but very wasteful. No doubt sponging consumes more
time, but taking into consideration the more effectual manner in which
the dressing can be executed alone, it is in the end most economical,
especially in regard to this little parasite. I have found it
difficult by syringing, as it has great power of resisting and
throwing off moisture, and if but a very few are left living, it is
astonishing how quickly it redistributes itself. I feel confident,
that by the application of this remedy in time another season, I shall
keep this collection clean. I believe planting the hollyhock in large
crowded beds should be avoided, as I have observed the closer they are
growing the more virulently does the disease attack them, whereas
isolated rows and plants are but little injured."[m]
The "Gardener's Chronicle" has also sounded a note of warning that a
species of Uredine has been very destructive to pelargoniums at the
Cape of Good Hope. Hitherto these plants have not suffered much in
this country from parasites. Besides these, there are many other less
troublesome parasites, such as _Uredo filicum_, on ferns; _Puccinia
Lychnidearum_, on leaves of sweet-william; _Uredo Orchidis_, on leaves
of orchids, &c.
If we would sum up the influences of fungi in a few words, it could be
done somewhat in the following form.
Fungi exert a deleterious influence--
On _Man_,
When eaten inadvertently.
By the destruction of his legitimate food.
In producing or aggravating skin diseases.
On _Animals_,
By deteriorating or diminishing their food supplies.
By establishing themselves as parasites on some species.
On _Plants_,
By hastening the decay of timber.
By establishing themselves as parasites.
By impregnating the soil.
But it is not proved that they produce epidemic diseases in man or
animals, or that the dissemination of their multitudinous spores in
the atmosphere has any appreciable influence on the health of the
human race. Hence their association with cholera, diarrhoea, measles,
scarlatina, and the manifold ills that flesh is heir to, as producing
or aggravating causes, must, in the present state of our knowledge and
experience, be deemed apocryphal.
[A] A detailed account of the peculiar properties of this fungus and
its employment as a narcotic will be found in Cooke's "Seven
Sisters of Sleep," p. 337. It is figured in Greville's
"Scottish Cryptogamic Flora," plate 54.
[B] Pour chaque 500 grammes de champignons coupes en morceaux
d'assez mediocre grandeur, il faut un litre d'eau acidulée par
deux ou trois cuillerées de vinaigre, ou deux cuillerées de sel
gris. Dans le cas ou l'on n'aurait que de l'eau à sa
disposition, il faut la renouveler une ou deux fois. On
laisse les champignons macérer dans le liquids pendant deux
heures entières, puis on les lave à grande eau. Ils sont
alors mis dans de l'eau froide qu'on porte à l'ébullition,
et après un quart d'heure ou une demi-heure, on les retire, on
les lave, on les essuie, et ou les apprête soit comme un
mets spécial, et ils comportent les mêmes assaisonnements
que les autres, soit comme condiment.--_Morel Traité des
Champignons_, p. lix. Paris, 1865.
[C] Smith's "Chart of Poisonous Fungi," fig. 10.
[D] Ibid. fig. 27. It would be well to become acquainted with all
these figures.
[E] "Skin Diseases of Parasitic Origin," by Dr. Tilbury Fox. London,
1863.
[F] Robin, "Hist. Nat. des Végétaux Parasites." Paris, 1853.
Kuchenmeister, "Animal and Vegetable Parasites of the Human
Body." London, Sydenham Society, 1857.
[G] Berkeley, in "Intellectual Observer," Nov., 1862. "Mycetoma," II.
Vandyke Carter, 1874.
[H] Hallier and Zurn, "Zeitschrift fur Parasitenkunde." Jena,
1869-71.
[I] Dr. Lauder Lindsay, "On Microscopical and Clinical Characters of
Cholera Evacuations," reprinted from "Edinburgh Medical
Journal," February and March, 1856; also "Clinical Notes on
Cholera," by W. Lauder Lindsay, M.D., F.L.S., in "Association
Medical Journal" for April 14, 1854.
[J] "Microscopic Examinations of Air," from the "Ninth Annual Report
of the Sanitary Commissioner," Calcutta, 1872.
[K] "Gardener's Chronicle," March 26, 1864.
[L] Gray, G., "Notices of Insects that are Known to Form the Bases of
Fungoid Parasites." London, 1858.
[M] Halsey, "Ann. Lyceum," New York, 1824, p. 125.
[N] Tulasne, "Selecta Fung. Carp." vol. iii. p. 17.
[O] "Berlin Entom. Zeitung," 1858, p. 178.
[P] "Smithsonian Contributions to Knowledge," v. p. 53.
[Q] "Wiegmann Archiv." 1835, ii. p. 354; "Ann. Nat. Hist." 1841,
405.
[R] Leidy, "Proc. Acad. Nat. Sci. Phil." 1851, p. 204.
[S] "Gardener's Chronicle," November 21, 1868.
[T] Corda, "Prachtflora," pl. ix.
[U] Leidy, "Fauna and Flora within Living Animals," in "Smithsonian
Contributions to Knowledge."
[V] Murie, in "Monthly Microscopical Journal" (1872), vii. p. 149.
[W] See genus _Mycetophagus_, "Stephen's Manual Brit. Coleopt." p.
132.
[X] Sowerby's "Fungi," plates 289 and 387, fig. 6.
[Y] Schacht, "Fungous Threads in the Cells of Plants," in
Pringsheim's "Jahrbuch." Berlin, 1863.
[Z] "Proceedings of the Agri. Hort. Soc. of India" (1871), p. 85.
[a] "Gardener's Chronicle" (1852), p. 643, with fig.
[b] Berkeley, "On the Potato Murrain," in "Jour. Hort. Soc." vol. i.
(1846), p. 9.
[c] De Bary, "Die gegenwartig herrschende Kartoffelkrankheit."
[d] De Bary, "Memoir on Peronospora," in "Annales des Sci. Nat."