Midland Naturalist/Volume 01/Economic Mycology

by J. Griffith Morris

Economic Mycology.^[1]

 

---

 

By J. Griffith Morris, Esq.

President of the Woolhope Naturalists' Field Club.

 

---

 

In the work of education during early life little is done to draw out and develop two of the principal faculties with which man is endowed—observation and manipulation. Habits of seeing quickly, observing accurately, and discriminating minutely are not acquired without learning to use the eyes. Nor are delicacy of touch with lightness, accuracy, and steadiness of manipulation without a similar education of the hands. Readiness and accuracy of investigation and observation are likely to be of more service to most men in everyday life than any amount of scholarship, whether classical or mathematical. Examining Boards are now doing much to enforce the study of science at schools, and the coming generation, not content with exclusively classical teaching, will go forth into the world better prepared to advance the material interests of mankind.

This earth is beautiful indeed,
And in itself appeals
To eyes that have been taught ta see
The beauties if reveals.—Montygomery.

From the study of any branch of Natural History two sources of advantage are to be expected—a beneficial result on the mental and physical powers cf the individual, and the practical utility of the knowledge gained. The student becomes a wiser and better man; be becomes elevated and refined, a love for the true and beautiful is created within him, and his enjoyments are increased in proportion.

Mycology is a subject with which the name of the Woolhope Club is especially connected; it well illustrates the truth of these remarks, and inasmuch as little progress can be male in its study without the aid of the microscope, additional educational advantages arise, for that instrument in itself demands the practice of patience, order, and observation, and develops the senses of sight and touch.

Mycology presents a wide and fertile field of research. The progress of recent science demonstrates more and more that the growth, reproduction, and life-history of minute funguses is of vast importance in the economy of nature. To their unseen causation are due most of those changes which affect organic life. Under their influences organic tissues alter their form of vitality.

What is called decay is in truth only a process to other forms of life, sometimes beneficial to man in the production of wholesome food, but more often injurious by causing disease and pestilence.

It is ten years since the Club commenced the study of Agarics, and that series of discussions and papers began which have since given so much renown to it. The subject was scarcely introduced when in the following year prizes for collections of funguses were for the first time given at South Kensington, and Dr. Bull took the chief prize for Herefordshire.

In the autumn of 1868 the first Fungus Foray was made to Holme Lacey, under the superintendence of our staunch friends, Messrs. Lees and Worthington Smith. These forays have gradually grown in interest, increasing numbers join them, and an abundant supply of papers notifying new facts and discoveries is annually read.

Many of the most distinguished mycologists have done us the honour of attending them. The Club will be proud to mention the names of Berkeley, Brooms, Cooke, Currey, Plowright, Phillips, Ronny, Vizo, Houghton, Percival, Cornu, De-Seynes, and several others who have again and again been present at our forays.

The active interest of our members in the study of funguses was at once excited by calling attention to the edible kinds. It was shown that a large amount of vegetable matter containing nitrogen, hitherto allowed to waste your after year, might be utilised as food. Experience has shown, however, that an ides so philanthropic is not in England practically feasible. Tew species of Agaric are edible, more are tasteless or disagreeable, and some that are poisonous are unfortunately too common.

The comparative scarcity of uncultivated land in this country, and the uncertain and, as it were, capricious growth of Agarics, pub quite out of the question any reliance on them as a source of food for the people, the more especially as other food is happily so abundant. It still remains, however, for the scientific epicure to distinguish and profit by them, as he assuredly may do, and gather from them as varied and delicious relish.

The study of Mycology deserves all the ardour with which it has been recently followed; to it we owe the knowledge of those destructive agents, the various kinds of moulds, smuts, rusts, &c., that are called blight. The term blight is too indefinite. It is indiscriminately applied to funguses, to insects, and to diseases caused in the young and tender parts of plants by sudden alterations in the temperature or the amount of moisture in the atmosphere. Most living plants and animals are at times more or less infested with funguses, which are nourished at their expense, very often to the eventual destruction of both. Some of these parasites attack man himself, as shown by the production of various kinds of ringworm and thrush. The belief is growing that diphtheria, cholera, low fevers, and other such complaints, may be caused by microscopic funguses. It is an unhappy fact that these parasitical pests take up a residence on those vegetables that are the most useful to man, viz., those which produce starch, Of these the cereals are the most important. Rust and mildew attack the leaves, stem, and bracts, while ergot, smut, and bunt attack the organs of fructification of barley, wheat, rye, oats, maize, rice, and other cereals.

The corn rust and mildew are the same species of Puccinia in different stages of growth. It may be found on almost every grass in every part of the world; but it seems to have a preference for wheat. General attention appears to have been directed to it for the first time in 1804, when Batter made drawings for George III. The wheat of that your continued only 694 parts of starch and gluten in 1,000 parts, instead of the 995 parts of the nutritious matter which if ought to have contained. In 1806 the quantity was absolutely reduced to 203 parts. In 1810-11-12, when wheat was at its highest price during the war, corn rust was so prevalent and severe, the foliage of the plants so eaten up with it, and in consequence the grain so small and shrivelled, that, much as it was wanted, it was not considered worth while to thrash it out. It has been noticed that severe attacks of corn rust have more than once been coincident with the appearance of cattle plague. The last time that the cattle plague was prevalent in this country the clothes of people walking through corn fields became orange coloured from the dusty spores falling on them.

Smut is individually a very minute fungus, and yet of all the corn parasites it most readily attracts attention. It is a species of Ustilago that attacks the anthers and ovaries of wheat, barley, oats, maize, and rice, plants whose fertility and well-doing are of the utmost importance. It appears as a white viscid fluid, which dries up into a sooty, pulverulent mass. A German some years since attempted to prove that this powder was simply a collection of diseased cells, and therefore not a fungus, but he was easily refuted, for he was shown in the microscope the germinating spores.

Bunt (Tilletia caries) is a concealed foe, its residence is in the growing seed, and it is not till the farmer takes his sample after thrashing that he detects the presence of this pest (the little bunch of pappus at the upper end of the seed is not white, as it ought to be, but dark and dusty.) On careful search he then finds some distorted grains containing a fetid powder, which under a microscope is seen to consist of brown reticulate spores. Of course the presence of much of this fungus would he detected in the flour by its colour and smell, but the millers get rid of the affected grains by rolling and blowing. This fungus has not been destructive for some years.

In northern and cold countries where the soil is poor, rye is almost the only cereal grown. This grain is peculiarly liable to the attack of a fungus called Ergot. It is often present in such large quantity that when ground up and eaten a train of peculiar symptoms is produced, called ergotism, and instances are mentioned in which the continued use of the diseased grain has caused death. The same fungus grows on some of our pasture grasses, and often occasions great mischief to cattle.

In some parts of France the peasantry do not object to eat mouldy bread, and in most instances with impunity; but the species of mould varies. and alarming effects have sometimes followed. These, together with experiments performed on animals, prove that bread in a state of mouldiness will cause death. M. Barral, the French analyst, who reported to his Government on these cases, advises "that as most people are unable to distinguish the species of mould, the use of all bread in such a condition should be avoided."

Next importance to corn as a starch producing vegetable is the potato. Many funguses attack it. The Phytopthera infestans, that is so very destructive, is one of the white moulds. The mycelium of this fungus is able to penetrate every part of the plant, discolouring and corroding the green parts, and causing loss of vitality and decay in the tuber. Partial observations of several mycologists had revealed much of its life history and mode of growth during the summer, but it was left for an honorary member of the Woolhope Club to discover how it survived the winter. It has Jong bean known that some funguses, like insects, go through several stages or metamorphoses. The final and perfect stage is easily recognised in mast insects, because that is the only one that has the power of reproduction; but among funguses every stage is able to propagate itself in some way; thus in summer the potato blight throws off from the free ends of its mycelial. threads two kinds of short-lived spores, which, if they fail on the leaf of a potato, germinate and quickly reproduce themselves, killing their victim and perishing with it.

Our friend Mr. Worthington Smith lad the good fortune, while investigating the natural history of this fungus, to discover another kind of spore, called a resting spore, because it hybernates in or on the ground, He watched its mode of formation in the autumn and its growth the following spring, and thus was enabled to prove that this spore was the long sought for means by which Peronospora infestans continues its existence from year to year.

This spore is to he found in the tissues of the decaying plant. It is formed by a process of conjugation not uncommon among funguses. By degrees it acquires a hard protecting coat, and, with the dying plant, falls to the ground, where it remains to take its chance during the winter. On the rectum of warmth, the hard coat bursts, mycelial threads exude, and extend in search of a foster mother. If they do not meet with a potato plant in growth, they speedily exhaust themselves, and die; but if unfortunately successful, they pierce the cuticle, and the work of destruction commences.

Through want of thought and custom, much is done that favours the existence and propagation of this pest—diseased haulm and tubers are left on the surface of the ground when the crop is taken up, and are afterwards dug in to serve as manure. If this happens in a garden or rental potato ground, and the same crop is put in a second year, a vigorous crop of Peronospore is the result, and the cottager scarcely gets his seed back. The potato blight is also extensively propagated in another way. It most houses it is usual to throw away diseased tubers along with parings and other rubbish into dust heaps, which are in due course carted away and used as manure. It is probable that staring potatos in the same buildings or floor year after year, favours the spread of the disease.

Mr. Worthington Smith’s discovery teaches that every part of an infected plant should be burnt; it is the simplest way of effectually destroying the fungus; and also, that under no circumstances should potatos be planted for two consecutive years in the same ground.

Parasitical fungi, not content with damaging corn and potatos, are also very injurious to garden produce; cabbages, beans, peas, celery, and onions, each of them cherish and faster some unbidden visitor; fruit trees, as pears, plums, peaches, filberts, and walnuts furnish a residence for some unwelcome intruder.

Flowering plants, grown for their beauty, are much injured, and sometimes killed, by parasitical funguses; witness the rose trees and hollyhocks. Two years out of three hopyards are rendered unproductive by attacks of an Erysiphe.

Timber trees do not suffer much while in growth, yet it is curious to number the varieties of fungus found on them. M. Wessendorf says that "seventy-four attack the lime, of which eleven reside on the leaf; 114 the spruce fir, and no less than 200 the oak;" among the latter are reckoned those funguses whose ravages in timber-built ships have occasioned a loss in fourteen years estimated at twenty millions, and which in church and domestic architecture produces great annoyance and expense by causing dry rot. Merulius lacrymonus, Polyporus hybridus, and a Thalephora are the funguses which prey on sound timber; their mycelium creeps between the cells, and decomposes the lignin and cellulose; the Merulius has a rusty-coloured irregular stemless pileus, from whose gills a liquid constantly exudes.

If the useful plants of other countries are examined, we find in the south of Europe olives, oranges, and onions damaged by a fungus that envelopes their leaves in a covering of soot: in the Atlantic isles and Frances the Oidium Tuckeri destroys the grape vine. This fungus first appeared in an English hothouse, and thence has spread in all directions. Our friend, M. Cornu, told us last October that another fungus had lately appeared on the vine at Narbonne, causing a disease called Anthracnose. In some parts of Italy the cultivation of the silkworm has been suspended because it is attacked and destroyed wholesale by a species of mould somewhat resembling that which kills flies in the autumn, and leaves them adhering to the glass in our windows, surrounded by a cloud of white spores. In America the maize in often much injured by a smut that causes large and curious distortions of the grain end cobs. The plant which of all others is the most important for clothing purposes—the cotton plant—has two formidable enemies. One attacks the leaves, the other the pads.

Some manufactures are much impeded by the growth of moulds. Bleaching cannot he carried on in the fields on account of moulds growing and causing unsightly and irremovable blotches on the fabric. The preparation of gelatine, maccaroni, lime juice, and wines requires precautions to be taken to prevent access of air containing spores of funguses. It would not be difficult to extend the list of noxious funguses, but enough has been said to show that man’s person, food, clothing, building materials, and occupations are all injured by divers species of fungus. In proportion to the amount of injury they cause, they become important. It must be desirable, therefore, that their structure, habits, and life-history should be carefully studied, so that advantage may be taken of every opportunity of lessening or preventing their injurious effects.

The chemical process of nutrition in funguses is not the same as in other vegetables. Funguses do not convert inorganic matter into organic compounds, They possess a vital force capable of overcoming the natural play of chemical affinities, and they live by appropriating the constituents of the compounds they are thus enabled to decompose, Fermentation is nothing more than the manifestation of this process of decomposition. Such fermentations as are not produced by the immediate action of living cells are called indirect. They are caused by the intervention of nitrogenous soluble matters elaborated by living cells. These soluble ferments are often stored up till circumstances require their alternative action. It would seem that most organic substances are subject to fermentative changes, often occasioned by a special ferment plant. There are other ferment plants besides those that are recognised as funguses. Sugar undergoes several direct fermentations—the alcoholic, lactic, vinous, and butyric. Alcohol by fermentation becomes acetic acid; albuminous matters and urea are transformed into ammonia by processes of fermentation.

It will be interesting to sanitarians to know that there is reason for believing that the conversion of ammonia into nitric acid is caused by the presence of a fungus: this process has been called nitrification. It goes on constantly in soil that is saturated with decomposing animal matter. The saltpetre of commerce is for the most part imported from India, and is obtained by washing it out of the soil. Nitrification has long been known and carried on artificially. Pasteur suggested that it might be a fermentative change, and soma recent experiments show that be was probably correct. MM. Muntz and Schliessing passed sewage water through a porous medium; for eight days there was no change in the amount of ammonia, but after that time ammonia disappeared and nitric acid took its place. This experiment is only explicable by supposing that germs of a ferment plant were present and took time to mature. This notion was confirmed by another experiment, which proved that the presence of antiseptic vapours suspended the action.

Among fermentations the alcoholic takes the first rank; it is the most familiar and the most easily studied. There has been considerable differences of opinion as to the nature of the plant which causes this fermentation, Most English authorities have considered till lately that it was a modified growth of a common mould called Penicillium. German mycologists make it into a genus belonging to the class Torulæ among funguses. They call the genus Saccharomyces, and include within it several species.

Common yeast is Saccharomyces cerevisiæ; the composition bakers use has very small cells and is called S. minor. The yeast that grows on malt liquor when left to spontaneous fermentation, as is the practice in Belgium, is S. apiculatus. Other species appear on musts of wines, and juices of stone fruit. The species that is so important in this district, because it affects the transformation of apple juice into cider, appears under the microscope to be identical with that which is found on malt liquor, viz., S. apiculatus. Pasteur has proved by a simple experiment that germs or spores of Saccharomyces exist on the surface of grapes. He introduced boiled grape juice into a series of thirty flasks; of these ten were immediately scaled up; into a second ten he dropped a minute quantity of liquid prepared by washing the surface of some ripe untouched grapes; info the third ten he passed some of the same liquid boiled. In forty-eight hours the first ten were unaltered, the second ten were in full fermentation and filled with flakes of mycelium, the third ten were unaffected. There is reason for believing that all saccharine fruits have on their surface spores which remain quiescent till a concurrence of circumstances brings them into contact with the enclosed juices, then subaqueous growth commences accompanied by the decomposition of the sugar. So long as the subaqueous growth continues propagation of the fungus takes place by budding, but as soon as the sugar is exhausted the fungus comes to the surface end forms spores. Saccharomyces cerevisiæ, or common yeast, is seen under the microscope to consist of a multitude of granular cells, diffused through a turbid liquid called yeast water. The cells are about 1-3,000 of an inch in diameter, and, like all other vegetable cells in their simplest stage, consist of a speck of jelly called protoplasm, enclosed in a non-nitrogenous envelope. Yeast is composed principally of albuminous and amylaceous matter, but it contains a large proportion of phosphates of potash and magnesia. The remarkable feature in its composition is its richness in nitrogen. Funguses contain more nitrogen than any other class of plants. The Chanterelle contains 3.62 per cent., Bolefus edulis 4.25, Lactarius deliciosus 4.60, mushroom, 7.26, and yeast 10, so that it closely approaches animal matter. Those Agarics have been selected for comparison because they have been often set before us at our Fungus Foray dinners. Knowing the chemical composition of yeast, we should expect the medium in which it flourishes to contain the nitrogenous and mineral matters which it requires. It has been proved by experiment that yeast will not exert its peculiar action on sugar unless these matters are present in solution.

We all know that if yeast be added to a liquor at a suitable temperature in which melt or some sacchharine fruit has been digested, certain occurrences will ensue. The liquor will slowly become turbid, effervescence will take place from the escape of free carbonic acid, the sweetness will disappear, alcohol will become evident to the taste and smell, and a large increase will take place in the bulk of the fungus.

There are several varieties of sugar much alike in their chemical composition and properties. The two principal are saccharose and glucose. Yeast acts differently on each, so that it will be well to trace back their relation to, and formation from, starch. Starch, chemically, is nothing more than carbon, combined with the elements that compose water in the proportion of six to five. It appears to be the first product of that decomposition of carbonic acid and assimilation of the carbon, which, under the influence of the sun's rays, is continually going on in growing plants. Starch is the basis from which most other vegetable secretions are formed. It is either used up at once by the plant that secretes it, or it may be laid by for future use; sometimes in the tuber as in the potato, in the seed as in corn, or in pith as sago. Saccharose, the sugar of commerce, or cane sugar, is made up, like starch, of carbon and water; but the proportions differ. Instead of six to five, in saccharose it is twelve to eleven. This sugar is found in the maple and beet; whenever found it is intended as a store for the future use of the plant at the time when a great and sudden demand is made for the purposes of reproduction. Glucose is the sugar met with in the grape and other fruits; it contains a little more water than saccharose and is more soluble. It is necessary that stored-up starch and saccharose should be altered into glucose before they are used by the plant. This alteration is always prepared for by the laying up of nitrogenous matter in close approximation with the stored material. When the food is wanted, the nitrogenous matter acts as indirect ferment, and causes the starch or saccharose, whichever it may be, to take up an additional quantity of water and become glucose. Thus the starch stored up in the barleycorn is altered into glucose when heat and moisture bring the nitrogenous matter called diastuse (which has been laid up under the cuticle) in contact with it, This process takes place in seeds when they germinate, and is taken advantage of by the maltster. For the same reason the tuber of the potato becomes sweet and transparent from the alteration of its sugar into glucose when growth begins. Again, when sugar cane and beet blossom a large supply of nutriment is suddenly wanted; the stored-up saccharose is then digested; that is, altered into glucose, and is carried away in the sap to the reproductive organs, to be there reconverted into starch, and stored up again in the seed. Parsnips and some other sweet roots that do not blossom the first year, lay up glucose itself, which is held in reserve till the next summer, then seed is formed and the root loses its sweetness and collapses.

If yeast be placed in water containing air or oxygen, the oxygen gradually disappears and is replaced by carbonic acid; a process exactly similar to the respiration of fishes, continuing day and night, but proportionately more active. The yeast would die when the oxygen was absorbed, but if glucose be then added, the fungus will abstract from it the oxygen required, and set free carbonic acid and alcohol. Pasteur, who has given great attention to the life-history of ferments, has concluded, after many experiments, that a continued supply of oxygen and the combustion it causes are necessary sources of energy for the development of vitality in ferment plants. As soon as the cells of yeast have exhausted the glucose in contact with them they have a tendency to come to the surface and take on their aerial growth, which is simply the formation of spores. Under favourable circumstances some of the cells at the surface may be observed under the microscope to form an additional internal membrane, which, becoming septose, divides the protoplasm into three or four parts; each of these parts becomes spherical, opaque, and is ultimately detached as a spore. The nutrition of yeast in one particular resembles that of the higher orders of plants, for if is supplied with a soluble nitrogenous ferment which enables it to alter saccharose. This nitrogenous matter may be separated by washing the cells in water, every time they are washed some of it is dissolved out, it is always acid, and if neutralised becomes again acid, directly that it comes in contact with saccharose the latter is forced to take up an additional atom of water and thus become glucose. The multiplication of the cells of yeast by budding is a process that may be easily watched under the microscope. If the temperature is kept between 75 and 90 degrees, one or more cells may be seen to arise in succession, or even at the same time, from a parent cell, and form themselves into short irregular chains. The vitality of yeast is dormant below 50, and is destroyed, as we should expect, at 140 degrees, for at that temperature nitrogenous matter begins to coagulate, The growth of yeast is checked it the solution of sugar is too dense, or if the quantity of alcohol is too large. Attempts have frequently been made by physiologists to account for these phenomena, but how and why carbonic acid and alcohol are substituted for sugar is still a mystery, and, like other mysteries connected with vitality, is likely so to remain. It has been ascertained that the weight of the alcohol and carbonic acid is nearly equal to the weight of the sugar which has disappeared. The slight difference is caused by the formation of other compounds that only appear in minute quantities. Some think that the glucose and other materials that form the food of the yeast plant penetrate the cell by osmose, and there, after undergoing transformation, we assimilated and converted into growing cells and tissues, while al the same time disassimilation is proceeding, the worn-out tissues ere changed into alcohol and carbonic acid, and are eliminated as excrementitious matter. This may be called the intra-cellular theory. Pasteur is of opinion that the vital action of the cell causes decomposition of the glucose, and that a portion of its oxygen penetrates the cell membrane and takes part in the process of assimilation, while the other constituents of the glucose are left outside free to arrange themselves into carbonic acid and alcohol. This is the extra-cellular theory. Which is correct? It remains for some one, perhaps a Woolhopian, to determine.

In this agricultural and woodland county there is abundant opportunity for the study, not only of the parasitic funguses, but of most others, and as our Field Club was constituted fer the purpose of observing and recording all facts connected with the Natural History of the district, it is to be hoped that some of our members will forthwith set up their microscopes and become students themselves. The facts observed at the time may often appear isolated and of little consequence, but subsequently by combination and further discovery they may become of the greatest value. Minute scientific research always precedes the application of science to industry, and, though little acknowledged, in at the present day performing a very important part in intellectual and industrial advancement, and will ere long effect great and unexpected changes.

---

1. Part of an Address read before the Woolhoape Naturalists' Field Club, at the Annual Meeting, held at Hereford, on April 23rd, 1878.