Fungi: Their Nature and Uses

by M. C. Cooke

Recently a case occurred at the Botanic Gardens at Edinburgh which was somewhat novel. The assistant to the botanical professor was preparing for demonstration some dried specimens of a large puff-ball, filled with the dust-like spores, which he accidentally inhaled, and was for some time confined to his room under medical attendance from the irritation they caused. This would seem to prove that the spores of some fungi are liable, when inhaled in large quantities, to derange the system and become dangerous; but under usual and natural conditions such spores are not likely to be present in the atmosphere in sufficient quantity to cause inconvenience. In the autumn a very large number of basidiospores must be present in the atmosphere of woods, and yet there is no reason to believe that it is more unhealthy to breathe the atmosphere of a wood in September or October than in January or May. Dreadful effects are said to be produced by a species of black rust which attacks the large South of Europe reed, Arundo donax. This is in all probability the same species with that which attacks Arundo phragmitis in this country, the spores of which produce violent headaches and other disorders amongst the labourers who cut the reeds for thatching. M. Michel states that the spores from the parasite on Arundo donax, either inhaled or injected, produce violent papular eruption on the face, attended with great swelling, and a variety of alarming symptoms which it is unnecessary to particularize, in various parts of the body.[K] Perhaps if Sarcina should ultimately prove to be a fungus, it may be added to the list of those which aggravate, if they are not the primary cause of, disease in the human subject.

II. What influences can be attributed to fungi upon animals other than man? Clearly instinct preserves animals from many dangers. It may be presumed that under ordinary circumstances there is not much fear of a cow or a sheep poisoning itself in a pasture or a wood. But under extraordinary circumstances it is not only possible, but very probable, that injuries may occur. For instance, it is well known that not only rye and wheat, but also many of the grasses, are liable to infection from a peculiar form of fungus called “ergot.” In certain seasons this ergot is much more common than others, and the belief is strong in those who ought to know something of the subject from experience, viz., farmers and graziers, that in such seasons it is not uncommon for cattle to slip their young through feeding on ergotized grass. Then, again, it is fairly open to inquiry whether, in years when “red rust” and “mildew” are more than usually plentiful on grasses, these may not be to a certain extent injurious. Without attempting to associate the cattle plague in any way with fungi on grass, it is nevertheless a most remarkable coincidence that the year in which the cattle disease was most prevalent in this country was one in which there was—at least in some districts—more “red rust” on grasses than we ever remember to have seen before or since; the clothes of a person walking through the rusty field soon became orange-coloured from the abundance of spores. Graziers on this point again seem to be generally agreed, that they do not think “red rust” has been proved to be injurious to cattle. The direct influence of fungi on quadrupeds, birds, reptilia, &c., seems to be infinitesimally small.

Insects of various orders have been observed from time to time to become the prey of fungi.[L] That known at Guadaloupe under the name of La Guêpe Végétale, or vegetable wasp, has been often cited as evidence that, in some instances at least, the fungus attacks the insect whilst still living. Dr. Madianna states that he has noticed the wasp still living with its incumbrance attached to it, though apparently in the last stage of existence, and seeming about to perish from the influence of its destructive parasite.[M] This fungus is called by Tulasne Torrubia sphecocephala.[N] About twenty-five species of this genus of sphæriaceous fungi have been described as parasitic on insects. Five species are recorded in South Carolina, one in Pennsylvania, found on the larvæ of the May-bug, and one other North American species on Nocturnal Lepidoptera, one in Cayenne, one in Brazil, on the larva of a Cicada, and one on a species of ant, two in the West Indies, one in New Guinea on a species of Coccus, and one on a species of Vespa in Senegal. In Australia two species have been recorded, and two are natives of New Zealand. Dr. Hooker found two in the Khassya mountains of India, and one American species has also been found at Darjeeling. It has long been known that one species, which has a medicinal repute there, is found in China, whilst three have been recorded in Great Britain. Opinions are divided as to whether in these instances the fungus causes or is subsequent to the death of the insect. It is generally the belief of entomologists that the death of the insect is caused by the fungus. In the case of Isaria sphingum, which is the conidia form of a species of Torrubia, the moth has been found standing on a leaf, as during life, with the fungus sprouting from its body.

Other and less perfect forms of fungi also attack insects. During the summer of 1826, Professor Sebert collected a great many caterpillars of Arctia villica, for the purpose of watching their growth. These insects on arriving at their full size became quite soft, and then suddenly died. Soon after they became hard, and, if bent, would easily break into two pieces. Their bodies were covered with a beautiful shining white mould. If some of the caterpillars affected with the parasitic mould were placed on the same tree with those apparently free from its attack, the latter soon exhibited signs that they also were attacked in the same manner, in consequence of coming into contact with each other.[O]

During the spring of 1851, some twelve or twenty specimens were found from amongst myriads of Cicada septemdecim, which, though living, had the posterior third of the abdominal contents converted into a dry, powdery, ochreous-yellow compact mass of sporuloid bodies. The outer coverings of that portion of the insect were loose and easily detached, leaving the fungoid matter in the form of a cone affixed by its base to the unaffected part of the abdomen of the insect. The fungus may commence, says Dr. Leidy, its attacks upon the larva, develop its mycelium, and produce a sporular mass within the active pupa, when many are probably destroyed; but should some be only affected so far as not to destroy the organs immediately essential to life, they might undergo their metamorphosis into the imago, in which case they would be affected in the manner previously described.[P]

The common house-fly in autumn is very usually subject to the attacks of a mouldy fungus called Sporendonema muscæ, or Empusa muscæ in former times, which is now regarded as the terrestrial condition of one of the Saprolegniei.[Q] The flies become sluggish, and at last fix themselves to some object on which they die, with their legs extended and head depressed, the body and wings soon becoming covered with a minute white mould, the joints of which fall on the surrounding object. Examples are readily distinguished when they settle on windows and thus succumb to their foe. Mr. Gray says that a similar mould has been observed on individuals of the wasp family.

A Gryllotalpa was found in a wood near Newark, Delaware, U. S., upon turning over a log. The insect was seen standing very quietly at the mouth of its oval cell, which is formed in the earth, having a short curved tube to the surface. Upon taking it up it exhibited no signs of movement, though perfectly fresh and lifelike in appearance. On examining it next morning it still presented no signs of life. Every part of the insect was perfect, not even the antennæ being broken. Upon feeling it, it was very hard and resistant, and on making an incision through the thorax it exhaled a fungoid odour. The insect had been invaded by a parasitic fungus which everywhere filled the animal, occupying the position of all the soft tissue, and extending even into the tarsal joints. It formed a yellowish or cream-coloured compact mass.[R]

The destructive silk-worm disease, Botrytis Bassiana, is also a fungus which attacks and destroys the living insect, concerning which an immense deal has been written, but which has not yet been eradicated. It has also been supposed that a low form or imperfect condition of a mould has much to do with the disease of bees known as “foul brood.”[S]

Penicillium Fieberi, figured by Corda on a beetle, was doubtless developed entirely after death, with which event it had probably nothing whatever to do.[T] Sufficient, however, has been written to show that fungi have an influence on insect life, and this might be extended to other animal forms, as to spiders, on which one or two species of Isaria are developed, whilst Dr. Leidy has recorded observations on Julus[U] which may be perused with advantage. Fish are subject to a mouldy-looking parasite belonging to the Saprolegniei, and a similar form attacks the ova of toads and frogs. Gold fish in globes and aquaria are very subject to attack from this mouldy enemy, and although we have seen them recover under a constant change of water, this is by no means always the case, for in a few weeks the parasite will usually prevail.

The influence of fungi upon animals in countries other than European is very little known, except in the case of the species of Torrubia found on insects, and the diseases to which silkworms are subject. Instances have been recorded of the occurrence of fungoid mycelium—for in most it is nothing more—in the tissues of animals, in the hard structure of bone and shell, in the intestines, lungs, and other fleshy parts, and in various organs of birds.[V] In some of the latter cases it has been described as a Mucor, in most it is merely cells without sufficient character for determination. It is by no means improbable that fungi may be found in such situations; the only question with regard to them is whether they are not accidental, and not the producers of unhealthy or diseased tissues, even when found in proximity thereto.