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The man of the world who desires to take part in | a scientific discussion; the lawyer who has to treat of a question of hygiene in the presence of experts; the engineer, the architect, the manufacturer, the agricul- turist, the administrator—all have to consider such questions, and they will find in this work clear and precise notions on microbes, notions which they wogld* find it difficult to glean from books designed for physicians and professional botanists. The questions of practical hygiene, those which concern domestic economy, agriculture, and manufac- tures, and which are connected with the study of microbes, must especially demand attention. These are pertinent questions in such a book as this. There is a certain danger in vulgarizing notions of medicine, strictly so called; but it can only be beneficial to make every one acquainted with the precepts of hy- giene, which cannot become popular until they have penetrated into the habits and routine of national life. There is much to-be done before modern society is practically on a level’ with the achievements of science; many prejudices must be uprooted, and many PREFACE. vii false notions must be replaced by those which are sounder and more just. For this reason, we have endeavoured to make ~ this work intelligible to all It may be read with profit by those who possess the elementary notions of natural science which are included in the course of primary instruction. We therefore hope that the volume may find a place in the libraries of secondary instruction, and in public libraries. Although the work is not specially intended for physicians, yet practical men may not be indisposed to glance at it: it may, at any rate, serve as an intro- duction to the much more learned works of Cornil and Babés, of Duclaux, Klein, Koch, Sternberg, ete. We have given an important place to the botanical question, which is too often neglected in works on microbian pathology. From this point of view, the narrow bond which connects bacteria with ferments and moulds has to some extent marked out the plan we have adopted; namely, that of passing from the known to the unknown, from what is visible with the naked eye to that which is only visible with the aid of the microscope. ANGERS, September 10, 1885. TABLE OF CONTENTS. goes INTRODUCTION, Microses anp Prorista ... on ove eee wee CHAPTER L Parasirio Foner anp Movnps eee eve oes eee I. General remarks on fungi on ove ees II. Basidiomycetes: uredines, the rust of wheat and grasses III. Ascomycetes : ergot of rye; mould of leather and dried fruit IV. Oomycetes, mucorinesx, or moulds, strictly so called ; pero- nospors; potato-fungus eee oe eee V. Parasitic fungi of the vine: oidium, mildew, etc. vs VI. Habitat and station of parasitic fungi: their destructive action ae on waa wer mee VII. Parasitic fungi of insects, considered as auxiliaries to man VIII. Muscardin, or disease of silkworms ... wae sie IX. Parasitic fungi of the skin and mucous membrane of man and other animals... see eos eos CHAPTER II. FERMENTS AND ARTIFICIAL FERMENTATIONS eee ave I. Definition of fermentation... ob eae tee II. Vegetable nature of ferments, or yeasts... ove eee III. Ferments of wine; alcoholic fermentation ... ove IV. Beer-yeast ... 0 os eee eee eos oes V. Concerning some other fermented drinks ... es VI. Yeast of bread ose eee oon soe eee PAGE x CONTENTS. CHAPTER ITI. MICROBES, STRICTLY 80 CALLED, OR BACTERIA eee I. The vegetable nature of microbes ose II. Classification of microbes, or bacteria ... ‘ies JIL. The microbe of vinegar, and acetic fermentation 1V. The microbes which produce the diseases of wine V. The microbe of lactic fermentation VI. The ammoniacal fermentation of urine ve VII. Butyric fermentation of butter, cheese, and sails VIII. Putrid fermentation, game-flavour ... 1X. Aérobic and anaérobic microbes ... oes X. The microbes of sulphurous waters... oon XI. The microbes which produce saltpetre XII. The microbes which destroy building materials XIII. The microbes of chalk and coal ... XIV. Chromogenic microbes eee vee eee XV. The microbe of baldness ee aes CHAPTER IV. Tur Microses or THE Diseases or Domestic ANIMALS I. Anthrax, or splenic fever eee or II. Vaccination for anthrax oes ove eos III. Fowl cholera... bate we ove IV. Swine fever 3 wee ss V. Some other diseases penal to damactie animals VI. Rabies wae ee VII. Glanders VIII. Pebrine and flacherie, dans ddieeuses of ‘ilewoviti CHAPTER V. Tyr Micropes or Human DIsEAses eee .I. Microbes of the air, the soil, and water ... Ii. Microbes of the mouth and digestive canal in a inesttbiy man oe ess III. The siden ce of fii sation eos IV. The microbes of dental caries V. The microbes of intermittent or marsh fevers VI. The microbes of recurrent fever and yellow fever PAGE 85 85 91 95 98 105 107 109 112 117 119 121 123 124 126 131 182 132 142 143 CONTENTS. VII. Typhoid fever and typhus oes eee oes VIIL. he microbe of cholera eee sat see ova IX. Eruptive fevers: scarlatina, small-pox, measles, cte. X. The mnicrobes of croup and whooping-cough ... aes XI. The microbes of phthisis and leprosy... XII. The microbe of pneumonia ... seo ioe ove XIII. Some other diseases due to microbes on ive XIV. The microbe of erysipelas ... eee ove oes XY. The microbes of pus, septicemia, etc. ae wes XVI. The microbes of other diseases, due to wounds ad XVII. The mode of action of pathogenic microbes: ptomaines “ CHAPTER VI. Protrcrion against Micropes as ies oe I. Antiseptic treatment of wounds: Giidrinre protective treat- ment; Lister's dressing ... Il. Hygiene of drinking - water: ater free foi siienabeat Chamberland filter ... Soe tas vee wis CHAPTER VII. Laporatory Resgarcu, AND CuLTuRE or Microses eee CHAPTER VIII. Po.ymonruism OF Micropes ae one ove eee CHAPTER IX, CONCLUSION ... on ove The Microbian Theory en with other Theories set forth to explain the Origin of Contagious Diseases aee wee APPENDIX. A. Terminology of Microbes or vee seo on B. Micrococcus of phosphorescence... oe ove C. Diseases of plants caused by bacteria... oe eee D. Ptomaine of the microbe of fowl cholera see eee E. Cesspools. System of conveying everything to the sewers F. Sewers of Paris and the Plain of Gennevilliers én G. Useful microbes vee eee one eee ee H. Ptomaines of fish our toe oe vee INDEX ... veo see one see woe vee 258 272 285 285 301 304 305 306 306 307 308 308 309 MICROBES, FERMENTS, AND MOULDS. INTRODUCTION. MICROBES AND PROTISTA, Microses are the most minute living things which the microscope permits us to see distinctly, so as to study their organization. They are for the most part invisible to the naked eye, and even by the aid of a simple lens. In order to form an exact idea of their forms and structure, we require the strongest magni- fiers of modern instruments, which enlarge the object 500, 1000, and even 1500 diameters. The. word microbe has been recently introduced into the French language; it did not exist eight years ago, and for this reason it will be sought for in vain in most dictionaries. It was under the following cir- cumstances that this term, now in such general use, was invented by Sédillot, an eminent surgeon, whose recent death is deplored by France. Those naturalists who have studied the most 2 MICROBES, FERMENTS, AND MOULDS. minute living things have at all times been at a loss to decide whether they have had to do with animals or plants. There can be no such doubt when we com- pare a tree of which the roots are fastened in the soil with a quadruped which moves freely on its surface. But these are highly developed forms, the one in the vegetable, the other in the animal kingdom. The lower representatives of the two kingdoms are, on the other hand, often so much alike as to baffle the most experienced naturalist. The animals which are assigned to the order of Zoophyta, or animal-plants, - have, as the name indicates, a form which led them to be for a long while regarded as plants ; many of them are fastened to the bottom of the sea or to rocks as if by actual roots, and, when superficially examined, their movements do not differ much from those which may be produced in true plants, as, for instance, in the mimosa. Many of the lower plants, belonging to the groups of Algz and Fungi, live in the water without being fixed by roots; many are animated by more or less apparent motion, at any rate during part of their existence, so that it is often somewhat difficult to dis- tinguish them under the microscope from those beings which are generally called Infusoria, and which are true animals. Hence it follows that the boundary between the animal and vegetable kingdoms remains indefinite, and that many of those microscopic organisms which MICROBES AND PROTISTA., 3 we have now to consider, may be assigned indifferently to one or the other kingdom. Bory de Saint-Vincent, a naturalist belonging to the early part of the century, and after him Heckel, have attempted to evade this difficulty by creating between the animal and vegetable kingdoms an inter- mediate kingdom, which they have named Protista, indicating thereby that it includes the first animals which in the geological ages appeared on the earth’s surface. This kingdom of Protista includes the fol- lowing groups, starting from the simplest and going on to those which are more complex :— *1, Monera (or Microbes, strictly so called; Schizomycetes, Bac- teria, Vibriones, etc.). . Amorphous Rhizopoda (or Amoebz), . Grogarinide. . Flagellata, . Catallacta. . Infusoria. . Acineta. . Labyrinthule, . Diatomacer. *10. Myxomycetes. *11, Fungi. 12, Thalamophora (Foraminifera or Rhizopoda with a calcareous skeleton). 13, Radiolaria (or Rhizopoda with a silicious skeleton). oMNAM oF & bd The groups marked with an asterisk are those which we propose to study in this work. For the most part, the organisms assigned to them resemble plants in their general characters, They are parasites which derive their nutriment from other living beings, For this reason, many of these organisms are the 4 MICROBES, FERMENTS, AND MOULDS. cause of the more or less ‘serious diseases which affect animals or plants. Naturalists who regard these para- sites as animals have termed them Microzoaria (from two Greek words signifying small animals). Those who regard them as plants have called them Micro- phyta (small plants), and it is still disputed which term is the most applicable to them. In other words; it is still undecided whether they should be classed in the animal or vegetable kingdom. It was at the Paris Academy of the Sciences, on the 11th of March, 1878, that Sédillot took part in one of the probably interminable discussions between the advocates of the Microzoaria and those of the Micro- phyta, and he suggested, with the critical sense for which he was distinguished, the word microbe, to which it appeared to him that every one could give their assent. In fact, the word microbe, which only signifies a small living being, decides nothing as to the animal or vegetable nature of the beings in question.* It has been adopted by Pasteur, and approved by Littré, whose competence to decide on neologisms is generally admitted ; it has been in common use in France for the last four or five years, and may now be regarded as definitively adopted into the French language. This word has not yet been fully introduced into * Béchamp terms microbes microzyma, or small ferments, since the chemical reactions which result from their vital activity are generally fermentations. MICROBES AND PROTISTA. 3) the English and German languages. In order to in- dicate the organisms which produce diseases, they make use of the word Bacteria, which is only the name of one of the peculiar species assigned to this group, and the one with which we have been longest acquainted. In this case, the name is generalized and applied to an entire group. The Italidn authors who have been recently occu- pied with the study of microbes have on their part adopted the name Protista, proposed by Heckel, and of which the sense, although not the etymology, is almost the same as that of the word microbe. In reply to the question whether there is any real advantage in establishing an intermediate kingdom of Protista between the two organic kingdoms of animals and plants, we must answer in the negative. This third organic kingdom only serves to render the structure of our modern classification more com- plex; and it includes, as may be seen from the list given above, a collection of very heterogeneous groups, which it would be more simple to leave in one or the other kingdom. We should, in our opinion, approxi- mate more closely to Nature’s plan by only admitting two great kingdoms: the organic kingdom, which includes plants and animals; and the inorganic king- dom of minerals, The organic kingdom should then be divided into two sub-kingdoms, animals and plants, of which microbes or protista, or whatever else they may be called, should form the connecting 6 MICROBES, FERMENTS, AND MOULDS. link, and testify to the common origin of the two great organic kingdoms. However this may be, we shall make use of the word “microbe” as the general designation of all the minute organized beings which are found on the borderland between animals and plants. We shall presently show that in the majority of cases these beings may be regarded as true plants, and this is at present generally admitted by most naturalists, Part played by Microbes in Nature—The part played by microbes in nature is an important one. We find them everywhere ; every species of plant has its special parasites, and this is also the case with our cultivated plants—with the vine, for example, which is attacked by more than a hundred different kinds. These microscopic fungi have their use in the general - economy of nature ; they are nourished at the expense of organic substances when in a state of putrefac- tion, and reduce their complex constituents into those which are simpler—into the soluble mineral substances which return to the soil from which the plants are derived, and thus serve afresh for the nourishment of similar plants. In this way they clear the surface of the earth from dead bodies and faecal matter; from all the dead and useless substances which are the refuse of life, and thus they unite animals and plants in an endless chain. All our fermented liquors, wine, beer, vinegar, etc, are artificially produced by the species of microbes called ferments; they also cause bread MICROBES AND PROTISTA. 7 to rise, and from this point of view they are pro- fitable in industry and commerce. But in addition to these useful microbes, there are others which are injurious to us, while they fulfil the physiological destiny marked out for them by nature. Such are the microbes which produce dis- eases in wine; most of the changes in alimentary and industrial substances ; and, finally, a large number of the diseases to which men and domestic animals are subject. The germs of these diseases, which are only the spores or seeds of these microbes, float in the air we breathe and in the water we drink, and thus penetrate into the interior of our bodies. Hence we see the importance of becoming acquainted with these microbes. Their study concerns the agri- culturist, the manufacturer, the physician, the pro- fessor of hygiene, and, indeed, we may say that it concerns all, whatever our profession or social position may be, since there is not a single day, nor a single instant, of our lives in which we cannot be said to come in contact with microbes. They are, in fact, the invisible agents of life and death, and this will appear more plainly from the special study we are about to make of the more important among them. Since it is easier to know and observe beings which are visible to the naked eye, we shall first speak of fungi—that is, of the larger microbes, with whose habits and organization we are also best acquainted. 8 MICROBES, FERMENTS, AND MOULDS. We will then go on to the study of the more minute ferments; and finally to that of bacteria (Schizophyta, or Schizomycetes), which are, strictly speaking, mi- crobes, and which only become visible with the aid of the microscope. * CHAPTER L PARASITIC FUNGI AND MOULDS. I. GENERAL REMARKS ON FUNGI. EVERY one is acquainted with the field and forced mushrooms, two varieties of one and the same species, wild or cultivated, and often seen at table. It is less generally known that the truffle is also a fungus; and that the large class of fungi includes moulds and many parasites which are more or less microscopic, which live at the expense of wild and cultivated plants, and attack animals and also the human subject. Fungi are among the lower plants, and differ from higher orders in their mode of life. It is well known that the large majority of plants are not nourished only by absorbing the mineral salts which, in a state of solution, their roots derive from the soil, but also, and chiefly, by decomposing the carbonic acid of the air, assimilating the carbon which, as cellulose, enters into the composition of all their tissues, and giving forth pure oxygen to the air. 2 10 MICROBES, FERMENTS, AND MOULDS. This function is not, as it was formerly erroneously supposed, a respiration in the inverse form from that of animals. All plants without exception breathe like animals by absorbing oxygen. The assimilation of carbon is a true nutrition, and as the decomposition of the carbonic acid gas which results from this assi- milation sets free a much larger quantity of oxygen than the plant requires for itself, it was for a long while believed that plants really breathed the car- bonic acid gas of the air, in the inverse method to that of animals. Fig. 1.—Agaricas in different stages of development: 2, 3, a vertical section showing the formation of the head. The byphx of the myceiium are shown in the lower part of the figure. The assimilation of carbon is effected by the leaves and green parts of plants; the green, granular sub- stance termed chlorophyll, which solely gives them this colour, as may be shown by the microscope, and which alone subserves this function cf nutrition. Fungi, however, have no leaves nor other green parts; that is, they have no chlorophyl. They derive the cellulose which they contain, as well as all the sub- stances by which they are nourished, either from PARASITIC FUNGI AND MOULDS. 11 other plants, or from animals and from the organic substances which are decomposing in the soil, such as dung and dead bodies. So that it may be said of fungi, that they subsist like animals by devouring plants or other animals; not like higher plants, which derive their nutriment from the soil or the air, and owe nothing to other living beings. It is for this reason that some naturalists have regarded fungi as animals, and have classed them in the animal kingdom. We have seen that Heckel and the naturalists of his school have assigned them to the kingdom of Protista. But setting aside their mode of nutrition, which is likewise found in plants of a higher, organization, such as the Orobranchee and some of the Orchidacew, fungi really exhibit all the characters of plants, and as such we shall here con- sider them, although they are plants of a peculiar and very low type. The class of fungi may be defined by saying that they are plants devoid of stems, leaves, and roots ; that they consist only of cells in juxtaposition, devoid of chlorophyl. They never bear a true flower, and are simply reproduced by means of very minute bodies, generally formed of a single cell, which is called a spore, and which represents the seed. In fungi of the highest type, such as that commonly known as the edible mushroom, the part which we eat and call the umbrella represents the flower or floral peduncle of other plants, and is in reality only 12 MICROBES, FERMENTS, AND MOULDs. the support or covering of the spores, which are fixed on the radiating lamelle that may be seen on in- verting the umbrella (Figs. 2 and 3). This umbrella or floral peduncle is the only part of the plant which appears above the soil, or the organic substances on which the fungus grows. But the really essential part of the plant is that Fig. 2.—Section of one of the lamella Fig. 3—Spores of the hymenium, greatly of the umbrella of Agaricus c: magnified, and resting on their supports a, b, spores of the hymenium or basides, a. (slightly magnified). which does not appear on the surface; namely, the white filaments or hyphe which creep along the soil, the manure, or whatever supplies the nutritive matter, and which represent at once the root, the stem, and tha branches of the plant; this part is termed the myceliwm. We shall presently see that many of the lower fungi are without the organ we have called the umbrella, and which botanists term the hymenium or organ of repro- duction, and consequently consist only of mycelium. PARASITIC FUNGI AND MOULDS. 13 In this case, the spores or seeds are developed in the cells of the mycelium itself. This latter mode of reproduction also occurs in the higher fungi, which therefore possess two modes, of reproduction and two kinds of spores: exogenous spores, which are externally developed, as we see on the hymenium (Fig. 2); and endogenous or internal spores, which are developed in the mycelium (Fig. 4). These spores not only differ in the site of their origin, but also in their form, size, structure; and in the end they fulfil in the reproduction of the fungus. There are in many cases several forms of exogenous spores. = Classification of Fungi.— as Eatin Or avons (much magnified). The nature of the spores, and the very varied mode of reproduction, have led to the classification of fungi in a certain number of groups, of which we need only cite the most im- portant, and those which chiefly concern our present point of view. Such are— 1. The Hymenomycetes. 2. The Basidiomycetes. 3. The Ascomycetes. 4. The Oomycetes. Each of these groups is subdivided into several sections or families. Ferments and Schizomycetes, or 14 MICROBES, FERMENTS, AND MOULDS. microbes, properly so called, are still often assigned to the class of fungi. We shall speak of them separately, and give our reasons for distinguishing them from true fungi. Hymenomycetes are the fungi which possess the hymenium or umbrella; all the edible species are included in this class, together with a great number of extremely poisonous species. They are generally of considerable size, and only a few among them are true parasites; they do not, therefore, enter into the plan of this work, and, in spite of the interest they present, we shall content ourselves with the brief notice of them we have just given. The other groups must, however, detain us longer. IL THE BAsIDIOMYCETES: UREDINES, THE RUST OF WHEAT AND GRASSES. The name of cereal rust is given to a parasitic affection caused by a minute microscopic fungus which is developed on the leaves of wild and cultivated grasses. This rust appears in the form of orange patches, which gradually spread over the blades of wheat and other grasses, and its common name is due to this colour. Many of the plants belonging to other families are attacked by analogous parasites, and these fungi are all assigned by naturalists to ‘the genus Uredo, and to the family of the Basidio- mycetes or Uredinew. PARASITIC FUNGI AND MOULDS. 15 Basidiomycetes have no endogenous spores, but they may have as many as four forms of exogenous spores. This is the case with the rust of wheat, termed by naturalists Uredo or Puccinia graminis, which appears in the spring on the blades of this plant. The patches of rust are covered with a fine dust, which, under the microscope, is seen to consist of small elongated bodies of a reddish brown, resting on a filament; these are the first 4 spores of the fungus, and are termed uredospores (Fig. 5). If they are scattered over a blade of wheat which was previously healthy, they germinate by means of a hypha of mycelium, which penetrates the leaf and develops a fresh patch of rust. In harvest- time the patches are of a darker, almost black shade, owing to the development of a second kind of Epcnia famine wakor Puceinia graminis, taken from a blade of wheat, and spore, These are pear-shaped, displaying several uredo- oes - . s Spores and one teleutospore divided in two, with an enveloping —_ (much magnified), membrane of considerable thickness; they are called teleutospores (Fig. 5). Teleutospores cannot germinate on a healthy blade of wheat, and consequently do not communicate rust. They may remain through the winter on thatch or wheat straw, awaiting the ensuing spring, and even then they cannot be developed upon a blade 16 MICROBES, FERMENTS, AND MOULDS. of wheat, but only upon the leaves of another plant, the barberry. Borne by the dew or by a drop of rain on to the young leaves of the barberry, the teleutospores germi- nate, and form reddish-brown patches which affect both sides of the leaf. On its lower surface the spores are smaller, ‘and are termed spermata ; their __ function is not thoroughly understood. The larger spores on the upper surface are called wcidiospores (Fig. 6), and with these we are more concerned, since Fig. 6.—S-ection of a barberry-leaf bearing two cecidiospores, more or less developed, of Puccinia graminis (much magnified). they are destined to return to the wheat, rye, or other grasses, in order to reproduce the original rust. When they are placed on a blade of one or other of these grasses, the cecidiospores germinate at once, and it is soon covered with patches resembling those of the preceding year; when these patches are numerous, they dry up the blade and destroy the ear. Hay and straw affected by rust should never be given to animals as food, since such food may produce disease. Thus it appears that Puccinia graminis presents the phenomenon of alternation of generations; that is, PARASITIC FUNGI AND MOULDS. 17 the complete development of the fungus is only effected by its transference from one plant to another. This phenomenon may be frequently observed in animal and vegetable parasites, and it seems to be designed in order to secure the preservation of the parasitic species, by permitting it to grow on two plants in succession, of which the development occurs at different periods of the year; such is the case with the barberry, which is developed in early spring, while wheat is developed in summer. For a long while it was believed that Ccidiwm berberidis, Uredo linearis, and Puccinia graminis were so many distinct species; but it is now known, as we have stated, that they are only three successive phases of the development of a single species.* Other Uredinece, constituting the modern varieties of Ustilago and Tilletia, are more apt to affect the ears of wheat and other grasses. This disease is termed by agriculturists smut or caries (Uredo carbo or Ustilago segetwm, and Tilletia caries). The diseased grain merely appears to be of a somewhat darker colour, but on pressing it between the fingers, there issues from it a blackish, oily pulp, which smells like rotten fish, Bread made from the flour of such corn has an acrid and bitter taste, and although it does not appear to be directly injurious to health, * So, again, Geidium rhamni (Nerprun or Bourdaine) produce Uredo rubigo-vera and Pueccinia coronata of wheat and oats. (See Fig. 7.) 18 MICROBES, FERMENTS, AND MOULDS. it cannot be regarded as fit for food. The dust arising from these fungi often produces in threshers in a barn an irritating cough, which ceases when they are no longer subject to the exciting cause. The verdet, or, as the Italians call it, verderame of maize is due to the presence of the same parasite (Ustilago segetum, Uredo carbo, or Sporisorium maidis) on the grains of maize, and for a long while it was believed to produce pellagra, a common disease among the peasants who live on maize. It is now known that pellagra is due to the growth of another fungus, much resembling the ergot of rye, of a) C) which we shall speak presently. Other species of Uredinew attack @ sorghum, rice, etc, and, indeed, very y many plants are affected by parasitic fungi belonging to the genus Puccinia ner a oe and to allied genera, and it is probable Uredo rubigoverm that they almost all present the phe- baie nomenon-of alternation of generations. A simple means of freeing our fields from the rust of wheat is indicated by what we now know of the alternation of generations which ensures the propaga- tion of this fungus. We must destroy all the barberry bushes which are found in the vicinity of cornfields, Popular opinion, although ignorant of the phenomenon of alternation of generations, has long regarded the neighbourhood of the barberry as the principal cause of the rust of cereals. PARASITIC FUNGI AND MOULDS. 19 In 1869, De Taste ascertained that in the parish of Chambray, after the peasants had uprooted all the barberries which grew in the hedges, the harvest, which had been bad in the foregoing year, was gathered in under normal conditions for three suc- cessive years. After the Lyons Railway Company had planted a barberry hedge to fence the railway in the parish of Genlis (Céte-d’Or), the cornfields bordering on the line were attacked by rust in an aggravated form, An inquiry made by the company showed that the disease was due to the barberry, and that where that plant was not found, the wheat was not affected by rust. On the other hand, a single shrub of barberry caused the disease to appear in a field in which it had never occurred before. The smut of wheat may be destroyed by the application of quicklime, either dry or dissolved in water, which destroys the fungus or checks its develop- ment, Seed corn should always be subjected to this operation when affected by smut. In default of quick- lime, sulphate of copper is sometimes used, which may be injurious, or sulphate of soda, dissolved in water (eight kilograms to the hectolitre). This should be done the day before the seed is sown. In the case of corn intended for food, another process called pelle- tage must be employed; this consists in the frequent stirring of the granaried corn, either with the hand or with Vallery’s movable granary floor, so as to dry and aérate it, and expel the dust and damp, which are favourable to the development of fungi. 20 MICROBES, FERMENTS, AND MOULDS. III. Ascomycetes ; Ercot oF RYE; THE MOULD oF LEATHER AND DriepD FRUITS. In distinction from the species just described, the fungi in this group possess endogenous spores, enclosed in a sac or special envelope which is called an ascus ; hence the name of the family. Truffles, or Tuberacee, are only reproduced by the spores contained in these asci; but most of the other ascomycetes present in addition several forms of spores, and the phenomenon of alternation of generations has led to the belief that in this case, as in that of the foregoing group, many of the so-called species are only successive transformations of one and the same species. This is the case with the ergot of rye, a product used in medicine; it is, however, a serious and dangerous disease of several of our cereals, and particularly of rye (Fig. 8). -Ergot is caused by a minute parasitic fungus which attacks the ear of rye when it is in flower. The young flower is covered with a white mass, consisting of microscopic spores, formerly termed sphaceliwm (Fig. 9). These spores reproduce themselves on other flowers, and propagate the evil. The mycelium formed by the germination of the sphacelium affects the grain, forms in it a thick felt- work, and is developed so as to constitute the elongated substance termed sclerotis (on account of its hardness), or ergot; it is called at this stage Claviceps purpurea. PARASITIC FUNGI AND MOULDS. 21 The sphacelium surrounding it falls off, and until the Fig. 9.—Sphacelium or Claviceps purpurea, the first stage of ergot Qnagnified), Fig. 8.—Ear of rye, on Fig 10.—Ergot bearing the organs which there are several of fructification (magnified). grains of ergot. following spring the ergot remains stationary on the soil on which it has fallen. 22 MICROBES, FERMENTS, AND MOULDS. In the spring, owing to the heat and moisture, the hyphe of the sclerotis swell and send forth numerous Fig. 11.—One of the heads or organs of fructification in ergot, still more magnified. a, peritheces, branches, bearing at their ex- tremity a sort of rounded head, in which the asci or peritheces are developed (Figs. 10, 11, 12); the endogenous spores issuing from these asci germinate on the rye-blossom, and produce there a fresh sphacelium, then a second ergot, thus always passing through the same cycle of alternation of generations. Most of the Graminacee and several Cyperacew are capable of producing ergots resembling those of rye, Fig. 12.—Portion of preceding figure under a very high magnifying power, showing at b the asci, and at c the spores issuing from the asci or peritheces, and possessing the same medical properties. The sug- gestion has been made that instead of the ergot of rye PARASITIO FUNGI AND MOULDS. 23 the ergot of wheat should be used in medicine; it is larger, harder, and more elongated in form, and it also appears to be less perishable. Ergot of rye, especially when powdered, strongly resembles meat in smell, and only becomes unpleasant when the powder is spoiled by being kept in a damp place; it then smells like rotten fish, and this is the case with many other fungi. At first the taste is not very apparent, but it after- wards produces on the pharynx a somewhat persistent sense of constriction. The chief action of this drug consists in producing contraction of unstriated muscu- lar fibres, especially those of the uterus. Ergotine and ergotinine are extracted from it, and these, which are its active principles, are often employed in thera- peutics in preference to raw ergot. In large doses ergot is a strong poison. It then produces characteristic symptoms, dilatation of the pupils, retardation of the circulation, vertigo, stupor, and even death. Bread made with flour from which the ergot has not been extracted may produce the grave symptoms known as ergotism, and these soon become fatal unless the use of such bread is discontinued. Sometimes nervous symptoms predominate, and this is termed convulsive ergotism; sometimes the disease takes the form of gangrene of the extremities, or gangrenous ergotism, but these two forms are only two phases of one and the same disease, and often occur in the same 24 MICROBES, FERMENTS, AND MOULDS. individual. In countries where rye bread constitutes the chief food of the rural populations, as in Brabant, the north of France, Orléannais and Le Blaisois, fatal epidemics have been recorded at different times in the Middle Ages, under the name of St. Anthony’s fire. The first symptoms are a species of intoxication, sought after by the peasants, and becoming habitual, like alcoholic drunkenness, up to the moment when con- vulsions and gangrene set in, and death soon follows. Ergot of maize produces analogous phenomena. In countries where maize bread and cakes are in use, | as in Italy and South America, it appears to be the cause of the disease improperly called Pelade. Of this the shedding of the hair and skin is the first symptom.* Fowls which feed on ergotized maize lay eggs which are devoid of shell, owing to their premature expulsion from the uterus; their combs become black, shrivel, and finally drop off; and they even shed their beaks. All these phenomena may be easily explained by the action of ergot on the muscular fibres of the uterus, and of the blood-vessels. Recent research has shown that Pelade is identical in its cause and external symptoms with the disease known in northern Italy and in the south of France as pellagra, and in Spain as the rose sickness. The latter * We shall presently see that the name Pelade was formerly given to another parasitic affection, peculiar to that part of the skin covered with hair. These two diseases must not be confounded, notwithstand- ing the similarity of name, since they are produced by two fungi belonging to different groups. a PARASITIC FUNGI AND MOULDS. 25 name is due to the red stains which cover the skin, afterwards drying up and falling off in the form of scales, At first the general health is not affected, and several years may intervene before the occurrence of vertigo, a want of appetite, emaciation, and finally the torpor and convulsions which precede death. These ill effects may be prevented by baking the maize before grinding it, ac¢ording to the process in use in Burgundy. There is another very common fungus also belong- ing to the group of ascomycetes, termed Lurotium repens. This mould appears upon leather which has been left in a damp place, and on vegetable or animal substances in process of decomposition or badly pre- served, and especially upon cooked fruits. This mould is of a sombre green, a colour by no means due to the presence of chlorophyl. On the mycelium, which spreads over the substance of the leather or of the fruit-skin, small stems are developed, consisting of a jointed tube, and terminating in an enlarged head on which chaplets of small grains are formed, each of which is a spore. This was formerly termed Aspergillus glaucus, and was regarded as a peculiar species (Fig. 13). When, however, this mould is developed in a place in which the supply of air is limited, small gold-coloured balls may often be observed beside or in the midst of the stems, and these are filled with asci, each containing eight spores. This second form has been termed Zwro- tiwm repens. It has recently been ascertained that 26 MICROBES, FERMENTS, AND MOULDS. the balls in question are produced from the same mycelium as Aspergillus glaucus, and that conse- quently the chaplet of stalks and the balls filled with asci are merely two organs of the same fungus. Fig. 13.—Aspergillus glaucus, mould on leather and rotten fruits : a, hypha bearing the chaplet of spores b; c,a germinating spore; d, ball of Eurotium; e, ascus enclosing the endogenous spores (magnified). The chaplet of spores in Aspergillus glaucus repre- sent the white exogenous spores, or the sphacelium of the ergot of rye, and those which are subsequently PARASITIC FUNGI AND MOULDS. 27 produced in the yellow balls correspond with those which issue from the asci developed on the sclerotis; these are endogenous spores. Many of the parasitic fungi belonging to the genera Evrysiphe, Spheria, Sordaria, Penicillium, etc., pre- sent a similar mode of vegetation, and affect a large number of plants. Such is the Oidiwm of the vine (Erysiphe Truickert) to which we shall presently revert. IV. Oomycetes, MucoriInE&, oR MOULDS, PROPERLY SO CALLED; PERONOSPOREZ; THE Potato-Funcus. Tn all the parasitic fungi of which we have hitherto spoken there is no sexual reproduction analogous to that of the higher plants; there are no male and female organs comparable to the stamens and pistil. This sexual reproduction exists in the oomycetes, although only in a very elementary form. In addition to the ordinary spores which we have noticed in other fungi, there are others termed oospores, which are formed by the fusion of the originally distinct contents of two different cells, In the family of the mucorinez, which includes most of the fungi 4. 44 smcor cané- commonly called moulds (Fig. 14), 45, Me ami (mam the two cells of which the contents ™** are fused together are similar. Jn the peronosporee, however, which includes the potato-fungus, one of the 28 MICROBES, FERMENTS, AND MOULDS. cells is larger than the other, and persists alone up to the moment when the oospore is mature. It must, therefore, be regarded. as the female cell; while the Fig. 15.—Reproductive organs of Mucor mucedo (much magnified). other, which is smaller and soon withers away, is the male cell. The mycelium of the oomycetes is developed in a more or less liquid medium, like all other decomposing and putrefying substances. The ordinary spores are PARASITIC FUNGI AND MOULDS. 29° very small, and are formed within a small enlargement (sporangiwm) borne on a free hypha of the mycelium. Their succession is constant and numerous as long as the plant is in a favourable medium in which it can flourish. The spores which are found in the same medium germinate, and reproduce a mycelium similar to that from which they had their origin. Fig. 16.—Reproductive organs of Peronospora calotheca (much magnified). The oospores may be as much as a thousand times larger in volume than ordinary spores. They are only formed when the growth of the fungus is on the wane, as, for instance, when the substance serving as a sup- port to the mycelium is drying off: a long period may elapse before they germinate (Figs. 15 and 16). 30 MICROBES, FERMENTS, AND MOULDS. Fig. 15 represents the reproductive organs of Mucor mucedo. 1 is the sporangium filled with ordinary spores; in 2, the wall of the sporangium has disappeared, so as to show the free spores round the central columella; 3 and 4 represent the germina- tion of these spores, giving forth their hyphe; 5 gives the conjugation of the sexual spores, which are fused into one large oospore, 6; of this we see the germina- tion in 7, and it produces a hypha terminating in a sporangium. Fig. 16 represents the same organs in a Perono- spora. In 1 we see the mycelium of the fungus penetrating the tissue of the infected plant; in 2, the fructifying apparatus containing the ordinary spores issues through a stoma, ramifies, and produces sporangia at the extremity of each branch; in 3 and 4 we see two spores which have issued from these sporangia germinating and penetrating the epidermis of a leaf through the stomata (a, 6); in 5 we see the conjugation which has taken place between two dissimilar cells: the male cell, smaller in size (antheridiwm) is applied to the large female cells (oogontum), and after this mode of fertilization it is termed an oospore, which is represented in 6. Mucor mucedo, and other species of the same genus, form the small downy tufts of a greyish white colour which may be observed on mouldy bread, rotten fruits, and on the excrement of horses, dogs, and rabbits. When examined under the microscope, the PARASITIC FUNGI AND MOULDS. 31 filaments of which these tufts consist display at their extremities the sporangia represented in Fig. 15, 1. On rotten fruits, the spores of these fungi germinate in five or six hours by introducing their hyphe through the epidermis. Sleepiness, which is only the first stage of rottenness, is, according to Davaine, to be ascribed to the action of these fungi. Fruit in this mouldy ‘condition is sometimes unwholesome. The potato-fungus, Peronospora infestans, is one of the most dreaded scourges of this valuable plant. It attacks the lower surface of the leaves and stalks, and appears in the month of July, in the form of brown patches. The long hyphe penetrate deeply beneath the epidermis, and will even propagate them- selves on the tubers. Among the causes which produce or promote this disease, agriculturists place the excessive moisture of the soil, setting the plants too late in the season, the use of bad seed, the premature and exhausting germination of the tubers before they are planted, and the use of fresh dung which is not sufficiently decomposed. The following process is indicated as likely to prevent the development of this parasite. In the spring, the first protective ridge should be prepared with a flat top, from eight to ten centimetres high, and from twenty-five to thirty centimetres wide. Tn the first fortnight of August, a second protective ridge should be earthed up, of which the edge should Be MICROBES, FERMENTS, AND MOULDS. be acutely sloped, and the stalks of the plant should be turned down into the furrow, so that any spores which may be on the leaves may be washed off them by the rain, and not come into contact with the stem and roots of the plant. It is probable that earth-worms diffuse the spores of this fungus, as well of those of many other microbes. According to Prillieux, beetroot is attacked by another species of Peronospora, which causes the leaves of the plant to wither and fall. The remedy consists in burning the dead leaves on which the oospores remain during the winter, or, at any rate, in not allowing them to be placed on the dung-heap. The mildew which affects the vine is also a species uf Peronospora (P. viticola) as we are about to show. V. Parasitic Funel oF THE VINE: O{pDIUM, MILDEW, ETC. The parasites of the vine are so numerous as to require a separate chapter. Some years ago, in 1870, fifty of them were enumerated by Roumeguére, a well- known specialist, and the number is now more than doubled. We shall only now speak of the more important, of those which are especially injurious to the vine, and which consequently are the most interesting to us. PARASITIC FUNGI AND MOULDS. 33 Oidium. — Oidium, or Erysiphe Tuckerti — so called from the name of the vine-grower by whom it was first described—has been longest known to us among these parasitic fungi. It belongs to the group of Ascomycetes, and appears to have reached us from America in 1845, in which year it was first observed in England. Thence it passed over to France. In 1847 it was noticed in the neighbourhood of Paris; and afterwards, in 1850-1851, in the south of France, where for twenty-five or thirty years it raged with such intensity as to threaten for some years the almost complete destruction of the vine- yards, a destruction which is now taking place under the attacks of another parasite, belonging in this instance to the animal kingdom: Phylloxera vastatria, The oidium, the white disease or meunier, was equally destructive in the vineyards of Madeira, so that it was necessary to uproot all the vines, and replace them by sound plants which were incapable of bearing grapes for some years. The oidium appears on the grape in the form of greyish filaments, terminating in an enlarged head, which contains an agglomeration of spores, not free or in a chaplet, as in Aspergillus (Fig. 13). These spores escape as fine dust, diffuse themselves in the air,and spread the disease afar with extreme facility. If a spore lodges on a vine-leaf under favourable conditions of moisture and warmth, it soon germinates, penetrates the epidermis by means of its hyphe, and 3 34 MICROBES, FERMENTS, AND MOULDS. forms floury patches which send forth a peculiar musty smell. : The oidium may remain latent on the vine-stock throughout the winter. In the spring it reappears in yellowish patches on the earliest leaves, on which it is rapidly propagated; the plant languishes, and the leaves become pale and, as it were, anzemic. Very dry weather is unfavourable to oidium, and so also are heavy rains, which wash the fruit and leaves, and carry away the spores on to the soil. The remedy consists in the application of sulphur to the infected vines. Flowers of sulphur is used, which acts upon the fungus by gradually setting free sulphurous acid. Under this influence the microscope shows that the superficial mycelium and the fragile spores dry up as if they were burnt (Ed. André). Three successive applications are necessary, and these are made with the help of a special instrument in the form of a pair of bellows, to which a rose is affixed, in order to disseminate the flowers of sulphur. The first application is made in spring, when the shoots are from eight to ten centimetres long; the second directly after the vine has blossomed; and the third when the grapes begin to ripen. The opera- tion in spring is the most important, and should be performed with the utmost care, so as to affect all the hybernating spores from which the succeeding generations would issue. Not only the upper and lower sides of the leaves must be dusted, but also PARASITIC FUNGI AND MOULDS. 35 the branches and the stock itself. The third applica- tion should be made early enough for the sulphur to have disappeared from the grapes before the vintage takes place, It is evident that its introduction into the wine would have the worst effect: in process of fermentation sulphuretted hydrogen would be given off, which is injurious to the alcohol, and this gas would give an unpleasant taste to the wine. The morning is the best time for applying the sulphur, since the dew enables the powder to stick to the leaves and branches; and it should be made on a fine day, since heavy rain would carry off the sulphur before it has time to act upon the oidium. The sulphur which ultimately reaches the soil below the vine is transformed into sulphate of lime, which is an excellent dressing for the vine. Mildew—This new parasite, of which the scientific name is Peronospora viticola, belongs to the group of Oomycetes. It also comes to us from America. It was imported into Europe in 1878, with the American plants destined to replace those destroyed by the phylloxera, and was rapidly diffused through France, and thence to Algeria. It appears in the form of irregular patches of a whitish colour, not very thick, and with an almost crystalline appear- ance like that of a saline efflorescence (Planchon). It has not the mouldy smell of oidium, and appears later in the season, generally on the autumn shoots. Its mycelium penetrates more deeply than that of 36 MICROBES, FERMENTS, AND MOULDS. oidium. Brown patches appear on the upper surface of the leaf, as if it had been scorched; and in corre- spondence with these there is a delicate down “like the whiteness of a slight hoar-frost” (Vaissier) on its lower surface. The hyphee issuing from the mycelium ramify at right angles, and these branches bear the spores, as in the potato-fungus, Peronospora infestans (Figs. 17,18). These numerous spores, diffused through the air, are powerful sources of contagion. Fig. 17.—Mildew : a, vertical section of a leaf, bearing tufts of Peronospora viticola on its lower surface; b, a withered leaf, bearing the winter spores (oospores) (x 20 diam.). This parasite destroys the tissue of the leaf, exhausts it, and finally causes it to wither and fall. Those which are least affected have only diseased patches. The bunch of grapes and the young herbaceous shoots are rarely affected. In addition to the ordinary or summer spores of which we have spoken, the sexual spores must be noted ; the oospores, or dormant winter spores, which PARASITIC FUNGI AND MOULDS. 37 hybernate in the tissue of the leaf itself (Fig. 17, b), and germinate in the spring. The conjugation of the sexual spores, as well as the ripening of the summer spores, and the germination of the zoospores which issue from them, can only occur in a drop of water, rain, dew, or mist, so that a persistent drought checks the propagation of this fungus. The parasite injures the stock by stripping it of its leaves, thus hindering the nu- trition of the plant; moreover, the grapes, since they are im- perfectly protected from the sun, dry up before they are sig. 1¢—Group of tufts of Pero ripe. Sometimes, also, the ee ee ere ie of fungus attacks the grape itself, ere aang or its peduncle. Vines planted in a moist soil resist its attacks better than others, simply because the nature of the soil makes the plant more vigorous, and suitable manure acts in the same way. When the fungus is developed, it may be destroyed by sulphur mixed with powdered lime. Since its mycelium is more deeply seated than that of oidium, it is necessary to have recourse to more vigorous measures in order to reach it. Powdered borax has also been pre- 38 MICROBES, FERMENTS, AND MOULDS. scribed, in the proportion of five grammes to a litre of water; also a solution of sulphate of iron, one kilogram to two litres of water, with which the stock should be washed fifteen days before the shoots begin to start (Millardet). Mme. Ponsot, in Bordelais, has used the same substance mixed with lime (four parts of powdered sulphate of iron to twenty parts of lime). The fallen leaves which contain the winter spores, or oospores, should be burnt or buried. The stocks should be irrigated as often as possible, and the leaves should be dusted with lime in order to dry off the dew or mist, which favours the fertili- zation of the oospores. Some species of vines resist the disease better than others, and this is the case with the Labernet, a vine from Médoc, which has remained almost entirely free from it in infected regions of Algeria, Anthracnosis, or Black-rot.—This fungus, of which the name is Phoma uvicola, or Sphaceloma ampelium, belongs to the ascomycetes. Of all the parasites of the vine it was the earliest known, but it was only in 1878 that its devastations were important enough to attract attention. Like the two preceding fungi, it is reproduced by spores carried afar by the slightest breeze. Heat and moisture are favourable to its pro- pagation, which is checked by drought. It appears on the young shoots in the month of May, in the form of round black spots which gradually spread over the twigs, leaves, and grapes PARASITIC FUNGI AND MOULDS, 39 The young stalks assume a sickly appearance, and often wither off, together with the leaves and fruit. When the fungus fastens on the fibro-vascular bundles of the leaves before their complete develop- ment, the leaves shrivel and curl up, and perform their functions imperfectly; when it attacks the petiole or peduncle of the bunch of grapes, it dries up, and the destruction of all the parts in dependence on it soon follow. It is this fungus which, under the name of rot, now devastates the American vineyards. Sulphur is by no means so efficacious in this case as it is with oidium, but the following treatment is prescribed by Portes :— 1. The prunings of the vine and other remains of the preceding years should be destroyed. 2. The suckers and young shoots should be dusted, in the second fortnight of April, with slaked lime which has been finely powdered, and this operation should be repeated once a fortnight up to the end of June. 3. Sulphur should be applied at the usual times, especially if there is any oidium. 4, The vines should be drained and irrigated as often as possible. 5. In all cases in which the fungus can be detected, powdered lime should be applied at the interval of some days, alternately with the same substance mixed with flowers of sulphur. Aubernage, called by the Italians the Black disease, must not be confounded with Anthracnosis. Accord- ing to recent researches, awbernage is not produced 40 MICROBES, FERMENTS, AND MOULDS. by a fungus, but by a degeneration which is either spontaneous or, as Pirotta and Cugini suggest, the work of bacteria, and which consists in the trans- formation of the cellulose and starch of the plant into dextrine, as Comes asserts, or, according to Pirotta, into tannin. This disease appears in three stages: (1) a simple discolouration of the sap, which assumes a tawny black shade without checking vegetation; (2) a begin- ning of necrosis, which renders the plant unhealthy ; (3) a complete necrosis, which affects the woody parts and arrests the growth of the plant. This disease is contagious, which leads us to believe that if it is not produced by a fungus, it is at any rate due to the development of a bacterium— that is, of a microbe. The remedy indicated by Italian naturalists con- sists in the application of salts of potassium, which may be extracted at small cost from the ashes of the vine branches which are burnt upon the spot. Resleria hypogea, or Rot.—This parasitic fungus is found on the vine-roots, and has been recently studied by Pyrillieux. The vine affected by this parasite languishes for some years and then dies. The evil spreads by means of the roots to adjoining stocks, and the parts affected spread like the patches formed by the phylloxera. The roots rot away. This disease has been widely spread in Haute Marne. This small fungus is distinct from one which bears PARASITIC FUNGI AND MOULDS. 41 the same French name, Pourridi¢é, which is found in the south of France, and has been studied by Planchon and Millardet. These naturalists describe it as formed by the rhizomorphous mycelium of a large hymenomycetous fungus, Agaricus melleus. Resleria is very different. It isa small white fun- gus, with a white or ash-coloured head, from eight to ten millimétres in size, of which the mycelium lives in the interior of the vine-roots, penetrating and profoundly affecting all the tissues of the roots, and producing in the autumn the fructification which comes to the surface. It is generally developed in marly and argillaceous soils, after a rainy season, and in the low-lying parts of vineyards on the slope of a hill. It thrives in the moisture which lies below the surface of the soil, and it is therefore important to improve the con- dition of those sub-soils which are impermeable. It is also necessary to separate the stocks, so as to prevent their roots from interlacing, and to uproot and burn diseased vines, since the fungus may subsist for several years in dead and dried roots. If, which is almost always the case, any fragments of roots remain in the ground, they will reinfect the sound stocks which have been substituted for them. Remarks on Diseases of the Vine—We may be surprised that this valuable plant, which has been so carefully cultivated in France, should be attacked by such a number of parasites, both animal and 42 MICROBES, FERMENTS, AND MOULDS. vegetable. Yet we should rather be surprised that the vine has not been completely destroyed by the combination of such diverse scourges, and that it has effectually resisted them in several regions of France. When we consider that for long years the same hoary old stocks have been required to produce grapes without truce or mercy, and often without taking pains to supply to them by a fitting manure the nourishment which is withdrawn from them by the fructification of the grape, we shall be less astonished at the decadence of our vineyards. And, indeed, enlightened minds ascribe the attacks of these numerous parasites to the weakness and exhaustion of our vines, rather than to any accidental cause, such as an importation from without. The principal remedy may, therefore, be found in restoring the strength of the vine by the planting of young suckers, and still more of seedlings. Instead of attempting to introduce foreign plants, which it may not be easy to acclimatize, and which will certainly be less valuable than the vines we have lost, it would surely be better to seek to regenerate our indigenous kinds by crossing the cultivated stocks with wild vines, or else, as Millardet suggests, by crossing them with each other. The attempt might also be made to graft the stocks from Bordeaux and Burgundy on wild or American vines, which offer a better resistance to the attacks of the phylloxera. PARASITIC FUNGI AND MOULDS. 43 VI. Hacrrar or Parasitic FUNGI: THEIR DESTRUC- TIVE ACTION. The habitat of parasitic fungi is extremely varied. Roumeguétre, in his Cryptogamie illustrée, has devoted more than forty pages of a large quarto, printed in three columns, merely to the enumeration of fungi, classified according to their position in plants, animals, organic or inorganic substances, and the author himself admits that this list is far from complete. Parasitic fungi are found on plants belonging to all the families of the vegetable kingdom, and also on other fungi; on living animals, vertebrate and invertebrate; on their dead bodies and on excrement ; in stagnant waters and in the sea, on piles and rocks. Others prefer marshes, turf-bogs, heathy ground (which may be marshy or dry), dunes, caves and holes, and even completely covered by the soil, as is the case with truffles. Others, again, grow upon stones, walls, and rocks; in the open air or in ruins; or, like Toruwla conglutinata and Himantia cellaria, in the darkest caves, where they form a species of feltwork, often several centimetres in thickness, of a blackish colour, ragged, and extremely light, which in the course of a few years overspreads the walls of cellars. Other fungi inhabit our houses, attack our food, clothes, utensils of every kind; wall-papers and books, of which the paste offers a nutriment which they can 44 MICROBES, FERMENTS, AND MOULDS. easily assimilate; linen; and even our toilet sponges, notwithstanding that they are in daily use. They may even be found on the most powerful chemical substances, on pastilles of sulphur, arsenical solu- tions, ete. “The general belief,” writes Roumegueére, “regards fungi as the result of decomposition. This belief is due to an imperfect acquaintance with the nature of these plants. Fungi are not only found on fragments of wood and decayed vegetables, but sometimes even on bare pebbles, on glass, on window-panes, on the lenses of microscopes, and on other polished surfaces. It must be supposed that fungi are able to extract the elements of nutrition even in such positions. Coprins, which have a surprising power of develop- ment, grow on amputated limbs. Young has recorded the appearance of a great number of these fungi, still in an imperfectly developed state, below the mattress on which a man was lying whose leg had been ampu- tated. The bed was cleaned, and in nine or ten days the fungus reappeared in the same abundance as before. Targionni-Tozetti had previously observed a similar growth on the apparatus which surrounded a fractured limb in St. George’s Hospital, Modena.” Berkeley states that immediately after the death of any vegetable substance, an army of fungi of various kinds is at hand to complete the work of decomposition. The soft tissues are rapidly reduced to a semi-fluid condition by the combined action of PARASITIC FUNGI AND MOULDS. 45 putrefaction and of these fungi. The hardest wood yields to the same agents, not indeed so quickly, yet much more rapidly than would be the case from the action of the constituents of the atmosphere alone. When a log of one of our finest trees is attacked by fungi, it soon becomes only a mass of rotten wood, of which the woody tissue has been traversed and destroyed by the mycelium. If the same log were merely subjected to the action of the weather, it might endure for half a century before becoming completely rotten. Merulius destruens (or M. lacrymans) attacks beams and the other pieces of wood used in building, and rapidly destroys them. The administrators of the Canal du Midi, Toulouse, were compelled to replace the oak piles which protect the sides of the canal as it traverses the town, on account of the ravages of Dematium gigantewm, one of the higher orders of fungi in its early form. At the end of the last century, the same fungus destroyed, in the course of two or three years, the Foudroyant, a sixty-gun vessel. In order to stop the development of these fungi in wood used for building, and especially in wood in- tended for ship-building, it is expedient, as soon as the trees are felled, to steep them in a metallic antiseptic solution—as, for instance, in sulphate of copper. An experiment made by Nageli, a celebrated 46 MICROBES, FERMENTS, AND MOULDS. botanist in Munich, demonstrates the action of micro- scopic fungi on organic substances, exclusive of any previous deterioration. “T enclosed,” he says, “several loaves in a tin case, which was carefully but not hermetically closed. When the case was opened at the end of eighteen months, the loaves were reduced to a small mass, consisting almost entirely of filaments of mould, in which I could detect no trace of the substance of bread. This mass was soft and moist, like a mud-pie. It emitted a strong odour of trimethylamin: no trace of starch remained. One hundred parts in weight of the original bread were transformed into sixty-four parts in their moist state, and seventeen parts after desiccation in the open air. The starch had been consumed in order to form carbonic acid and water.” Badham sums up in a few words the destructive effects of microscopic fungi. “Mucor mu- cedo,” he writes, “devours our pre- serves; Ascophora mucedo turns our bread mouldy; Molinia is nourished at the expense of our fruits; Mucor herbarium destroys Fig. 19.—Chetonium char- the herbaria of botanists; and tutum, mould on paper. . . Chetoniun chartatum (Actino- spora) develops itself on paper, on the insides of books, and on their binding, when they come in contact with PARASITIC FUNGI AND MOULDS. 47 a damp wall (Fig. 19). When beer or sweetmeats turn sour, it is the work of a fungus.” VII. Parasitic FuncI or INSECTS, REGARDED AS ALLIES OF MAN. Many microscopic fungi attack insects, both living and dead. We have all seen the bodies of flies still sticking to the window- pane or curtain, and surrounded by a species of aureole formed by the growth of a fungus, Penicillium racemosum, Me eeeiiel ie or sometimes Sporendonema muscee or taaafea Saprolegnia feraw, of the family of Oospores (Figs. 20, 21, 22). Cordiceps attacks certain caterpillars of the genera Cossus and Hepialus, when they are buried in the sand before their metamorphosis into chrysalides, and kills them by the development of its mycelium in their tissue. These caterpillars may often be found, bearing on their backs a fungus longer than them- selves (Fig. 23). Spheria militaris, a parasite to Bombyx pityocarpa, the caterpillar found on pine-trees, represents one of the few fungi which may be regarded as beneficial to man, since it destroys multitudes of these cater- pillars, and thus neutralizes the ravages caused by their devouring the young shoots and pine needles. In the Antilles there is a wasp called the vegetable 48 MICROBES, FERMENTS, AND MOULDS. wasp, because it is attacked during its lifetime by a fungus which it carries about for some time, and which finally causes its death: this is Torrubia spherocephala (Tulasne). Jsaria sphingwm, another BESS eeeee Py iS eee hes GSR a i Ts . Fig. 21.—Two filaments of Sapro- Fig. 22.—Oogonium of Saprolegnia legnia containing spores (greatly surrounded by Antheridia (much magnified). magnified). species of the same. genus, has been observed on the back of a butterfly, which was poised upon a leaf as if alive, and which was probably killed by the development of the fungus. These and other facts, not to speak of the muscardine of silkworms, to which we shall return, PARASITIC FUNGI AND MOULDS. 49 have given rise to a surmise that if we could discover the parasitic fungus of the phylloxera, we might transform it into a powerful auxiliary of agriculture, since by its aid the parasitic insect which now ravages our vineyards might be destroyed. From this point of view Giard has observed several of these parasites of insects, which he calls Entomo- phthoree, from the name of their prin- cipal genus, Entomophthora. Such is E. rimosa, which attacks grasshop- pers and the diptera of the genus Chironomus, enveloping them in a thick wee feltwork formed by the winter spores, rig. 23.—-Butterfly- and speedily killing them. In the Condi. =" same manner Isaria pulveracea attacks Pyrrhocoris apterus, an insect which is often injurious to our kitchen gardens. . It has been asked whether Entomophthora Plan- choni, the parasite of the aphis, might not also prey upon the phylloxera, but the experiments made in this direction have not hitherto been so successful as to allow us to count on this means of averting the scourge. With the same object, Hagen has suggested the use of beer-yeast, which seems to have a destruc- tive effect on insects, as it is developed in their tissues. 50 MICROBES, FERMENTS, AND MOULDS. VIII. MuscaRDINE, THE DISEASE OF SILKWORMS. Muscardine, which is caused by a true fungus, Botrytis bassiana, must not be confounded with other diseases which attack the silkworm, such, for instance, as pebrin, which, as Pasteur asserts, is caused by a bacterium, or, strictly speaking, a microbe, and, accord- ing to the recent researches of Balbiani, by Psoro- spermia. We shall presently revert to this disease. Botrytis bassiana is a true mould, belonging to the group of Oomycetes, and allied to the potato- fungus, Peronospora. It is propagated by spores, which, when falling on a silkworm, germinate and penetrate its body. A mycelium is then developed, which may take possession of the whole caterpillar without appearing externally. The germination is rapid in proportion to the age of the silkworm. When death has been caused by the develop- ment of the mycelium, hyphz appear through the animal’s skin; these soon bear white, chalky spores, which are readily detached and float in the air in im- palpable dust like smoke. The silkworms on which the dust falls do not appear to be diseased, and eat with avidity, but they die suddenly. It takes from 70 to 140 hours to develop the spores and: spread the contagion. It is difficult to free the breeding- houses from all the silkworms which die in this manner; those which die after having crawled up to the heather to prepare for their transformation & PARASITIC FUNGI AND MOULDS. 51 into chrysalides are only thrown away when they are found on removing the cocoons. The clouds of dust dispersed by the silkworms perpetuate the disease in the best-ordered factories. When the heather is thrown out of window, and the rooms are swept to get rid of the dust, the spores float in the air and are dispersed by the wind. Damp favours the development of the fungus, and the introduction of healthy silkworms into an infected breeding-house will not extirpate the disease. In order to attain this object, it is necessary to get rid of all the dead silkworms before the development of the spores, and to destroy their bodies by burning them with the heather, or with quicklime. The breeding- houses should then be completely emptied, and the compartments should be purified and disinfected in the ordinary way by fumigation with sulphur, and washed with chlorine water, before fresh silkworms are placed in them. IX. Parasitic Funer or THE SKIN AND Mucous MEMBRANE OF MEN AND ANIMALS. The skin-diseases of man and animals which are termed tinea are caused by the presence of parasitic fungi, just as the itch is produced by the presence of animals belonging to the group Acarus. These diseases are rendered eminently contagious by the dissemination of the spores of these fungi, which will 52 MICROBES, FERMENTS, AND MOULDS. germinate wherever the conditions of heat and moisture are favourable, even on a healthy skin, or where it is only irritated by a simple scratch. Ringworm, Achorion Schenlenti, the fungus which produces this disease on the parts of the skin covered by hair, belongs to the same family as oidium. Its mycelium produces hyphe, bearing chaplets of spores, as in the Mucorinese, but there is no true sporangium. Fig. 24.—Achorzon Schenlenti, fungus of ringworm (x 400 diam.): a, spores; b, chains of spores; ¢, mycelium. They are found in abundance in spots of ringworm, amidst the sulphur-coloured substance which carpets them. If a morsel of this substance is dissolved in ammonia, the fungus is detached, and may be observed under the microscope, especially if care has been taken to stain it brown by an aqueous solution of iodine (Pig. 24). PARASITIC FUNGI AND MOULDS. 53 The mycelium consists of elongated, cylindrical articulations, which find their way among the cells of the epidermis, especially in the vicinity of the edges of the patch, and may penetrate deeply into the dermis (Fig. 25). Some of the shorter filaments terminate in Fig. 25.—Transverse section of skin, on the level of a spot of ringworm: a, epidermis ; b, superficial layer of dermis; c, deep layer of the dermis; dd’ mycelium with spores. chaplets of spores, which are successively detached from the stem; they are therefore found detached in large numbers in the midst of the epidermic cells. The centre of the patch is occupied by one or more still 54 MICROBES, FERMENTS, AND MOULDS. infected hairs, surrounded by spores; but, while the centre is in process of healing, the fungus extends to the periphery and continues to spread. The raised surface of the patch is formed by this parasitic growth, which forms a circular excrescence, always increasing in size, while raising and thickening the epidermis. The parts affected by the mycelium are characterized by a slight suppuration throughout the patch; the indurated tissue is gradually absorbed, leaving deep scars which persist after a cure has been effected. The mycelium is found on infected hairs between the coats of their bulbous roots, while the numerous spores are only found between the epidermic layers of the hair. This fungus may be inoculated in all parts of the skin, but its favourite site is the head, where it pro- duces the disease long known as ringworm, or favus. It has been already said that fungi prey upon each other. Thus Achorion has fora parasite Puccinia favi, a minute fungus of a reddish-brown colour, which is often developed on the whitish epidermic scales which cover the mycelium on fresh spots of ringworm. The same parasite has also been observed on Pityriasis. Trichophyton tonsurans.—This fungus, allied to the preceding, subsists likewise on skin covered with hair, and produces tinea tonswrans. It is formed of a mycelium with two sorts of hyphe, some simply nutritive, others with short articulations, separating into chaplets of rounded PARASITIO FUNGI AND MOULDS. 55 spores, which are continually detached (Fig. 26). The “) geen i eer Fig. 26.— Trichophyton tonsurans on the epidermic layers of a patch of circinnate herpes: a, spores; b, mycelium with long articulations; c, mycelium witb short articulations (x 400 diam.). mycelium is often ramified, and penetrates within the epidermic cells, especially at the base of the hairs. It is probably that the parasitic Sycosis which affects + the beard, and_ circinnate herpes, two other skin-diseases, _ Bld ies Fig. 27.—Spores and filaments of are only varieties of the same ees soniae oe disease. .In fact, Cornil and Ranvier have ascertained that if Trichophyton is in- serted in the glabrous chin of a child, it will produce 56 MICROBES, FERMENTS, AND MOULDS. herpes; and that parasitic herpes may also be pro- duced on the back of the hand by the transference of the fungus from a patch of Timea tonsurans. The fungus may be transmitted to cats, dogs, and horses, who thus become agents of the contagion. A fresh study of the disease has been recently made by an Englishman, Dr. Thin, and he also regards it as identical with herpes, or Tinea circinata, According to this observer, the contagion is not transmitted by floating spores, but only by direct contact, and especially by the exchange of hats and caps so common among school.children. Experiments in artificial culture in milk, carrot- juice, or aqueous humour show that the fungus cannot be developed when the hair on which the spores are is entirely submerged; a certain degree of moisture is, however, necessary, which is probably more frequently found on children’s heads. In adults, the bulbous root of the hair is dryer between the follicle and the skin. The parasite may be destroyed by causing an inflam- mation of the part affected, since the serous effusion thus produced places the hair in the same conditions as in the cultare-liquids in which it is completely covered, and not floating. Pityriasis versicolor is produced by a fungus resembling the foregoing, termed Microsporon furfur. It grows between the cells of the epidermis, and effects their rapid degeneration. The hyphz have long articulations, intermixed with round spores, not PARASITIC FUNGI AND MOULDS. 57 arranged in a chaplet, but grouped below the epidermis (Fig. 28). The development is very slow, ES Fig. 28.—Microsporon furfur : a, b, groups of spores; c, mycelium with long, trans- parent, and curved articulations. but the fact of its inoculation can be established, and artificial cultures may be made. In the two parasites of which we have now to speak 4 58 MICROBES, FERMENTS, AND MOULDS. we cannot recognize any mycelium, and in this par- ticular they are allied with the ferments, of which we shall speak presently. The fungus consists of round cells, which multiply by budding. De Lanessan regards them as a separate group, to which he gives the name of Microsporex, while he designates those parasites of skin covered with hair which possess a distinct mycelium under the name of Trichophyta. The Pelade Fungus.—Pelade is another disease of Fig. 29.—Pelade fungus: epidermic cells, charged with spores (x 500 diam.). the skin covered with hair, which is caused by Micro- sporon Audowini, and which presents the characters just indicated. It would, therefore, be an error to give it the same generic name as Microsporon furfur, a fungus of which the mycelium is well developed, if the recent researches of Grawitz, to which we shall presently return,* did not tend to snow that Microsporeze and Trichophyta are only forms of the same parasite in different phases. * See chapter on Polymorphism of Microbes. PARASITIC FUNGI AND MOULDS. 59 The pelade fungus develops in the superficial horny layer of the epidermis, on the surface of the epidermic cells, and in their interstices. It does not penetrate the hair-follicles, and is only occasionally found on the hairs, in which case it is fastened to the detached pellicles of the epidermis, not to the interior * £000. 4 s o © m 7 2 WY O (©) 43 m= 40g | 0acg O © éo Fig. 30.—Hair affected by the Fig. 31.—Isolated spores, taken from mpi progress of Pelade patches of pelade: 1, 2, 3, 4, large ‘calvante. It is surrounded spores; 5, budding spores; 6, 7, 8, by epidermic cells charged empty spores; 9 to 12, small spores with spores (x 208 diam.). (x 1000 diam.). of the hair (Figs. 29, 30). It is composed entirely of the round spores already described, which are re- produced by budding (Fig. 31). The Fungus of Pityriasis capitis simplex.—lt is very similar to the foregoing, and is likewise seated 60 MICROBES, FERMENTS, AND MOULDS. in the horny layer of the epidermis, on which it produces a roughness in the form of dusty pellicles. It penetrates the hair-follicles, but not deeply, and only in the vicinity of the point at which they emerge. The spores of which it entirely consists are generally of an elongated form, and give off buds. According to Mallassez, this fungus is the prin- cipal cause of alopecia; that is, the shedding of 6 0 8 @ © oe 4 66 6 ¢ 88 ad Fig. 32.—Epidermic cell of skin Fig. 33.—Isolated spores, taken covered with hair, affected by from pellicles of Pityriasis Pityriasis simplex, and covered capitis simplex: a, full spores; with spores (x 1000 diam.). b, empty spores ; ¢, full spores budding ; d, the same empty (x 1000 diam.) hair, and the baldness which eventually ensues from it. It acts in two ways: (1) its presence and multi- plication disintegrate the epithelial layers; (2) the foreign body irritates the epidermis, producing exces- sive activity in the evolution of cells, and consequently the incessant desquamation which is the most apparent symptom of the disease. The shedding of hair is chiefly due to obstruction in that portion of the hair-follicle which underlies the orifice of the sebaceous glands, and PARASITIC FUNGI AND MOULDS. 6] this checks the regular development of the hair. The consequent irritation of the follicle produces hyper- trophy; this leads to the shrinking and finally to the obliteration of the follicle, and after languishing for a while, the hair falls off. Thrush (Oidiwm albicans).*—This fungus generally appears on the mucous membrane of the mouths of infants, especially of those brought up by hand, and which have been accustomed to the use of a sucker. The saliva becomes acid, and the white spots which constitute thrush (Fig. 34) appear in several places, especially on the tongue, the gums, and the soft palate. This plant is composed of two elements: of hyphe, and of spores, which adhere closely to the mucous membrane. The spores become elongated and con- verted into hyphz, which are segmented and ramified as their length increases; and they produce spores by division of the terminal cell, or sometimes by endo- genous formation within the hyphe. Thrush sometimes occurs in adults in certain diseases, such as phthisis and typhoid fever, especially when the patient eats little and is imperfectly nourished, which is frequently the case in serious or protracted illness. It is easy to destroy thrush by washing the mouth with Vichy water, or a solution of bicarbonate * Oidium albicans, Robin; Saccharomyces albicans, Rees; Sacch. mycoderma, Grawitz. (See chapter on the Polymorphism of Microbes.) 62 MICROBES, FERMENTS, AND MOULDS. of soda, which neutralizes the acidity of the saliva. It is, above all, essential that the feeding-bottle, all the utensils employed for the infant, and the infant itself, should be kept perfectly clean; and, unfortu- nately, this condition is too rarely fulfilled, especially TE eerie aaa ge, giving Wen aey & B thee ae ei a among the working classes in towns, and districts in which children are usually put out to nurse. The feeding-bottle in use in such cases generally smells so sour as to be offensive to every one who is not PARASITIC FUNGI AND MOULDS. 63 accustomed to it, and under these conditions thrush is almost certainly developed, so that few children escape an attack. It is not generally dangerous, yet it may, in some cases, compromise the health, and even cause the death of the child. In addition to care about cleanliness, a little pinch of bicarbonate of soda may be put in the feeding-bottle; this prevents the milk from turning sour, Onychomycosis —This disease, which attacks the nails of men and the hoofs of uni-ungulates (the horse, the ass, and the mule), is caused by a parasitic fungus of the genus Achorion (A. keratophagus). In man it is termed dry caries, and it is a fungus which is readily transferred from man to the animals with which he has to do, just as Achorion Schenlenit of ringworm passes from man to the dog, cat, rat, horse, ox, and perhaps even to rabbits and gallinaceze. In uni-ungulates the fungus is introduced into the cracked and superficial layer of the hoof through its. fissures. In order to destroy it, this external layer must be removed, and for greater security an anti- parasitic treatment should be used. This remedy cannot be applied to the human subject without causing considerable pain; yet the nail may be pared and scraped, and the anti-parasitic remedy can then be applied. Prevention and Cure of Skin-diseases.—The general custom of going to a common barber to have the hair dressed or cut must conduce to the dissemination of 64 MICROBES, FERMENTS, AND MOULDS. the fungi which attack those parts of the skin clothed with hair; the brush, the comb, or razor which passes successively and on the same day over hundreds of heads or chins must necessarily, if only in one case out of ten, carry the spores of the parasite from one person to another. The parasitic diseases of the hair are extremely persistent, and precautions as to cleanliness will not always effect a cure. The mixtures sold by hair- dressers under the name of capillary water, lotion to eradicate scurf, etc., should all be rejected. Experience shows that wetting the head often favours the development of the fungus, which may, indeed, remain stationary for two or three days, but which becomes more vigorous as soon as the head is dry. Sulphur and its compounds are successful in such cases, as well as in the parasitic diseases of plants. It would be best to apply this remedy in the form of a dry, impalpable powder, as in the application of sulphur to the vine, but this cannot be done without in- conveniences to which the persons affected do not readily submit; it might, however, be tried by those whose hair is naturally greasy. In other cases, and especially in those in which the hair is dry, as it usually is in persons affected by Pityriasis capitis, pomades must be used, although it has been asserted, but not proved, that fatty substances afford nourish- ment to the fungus. However this may be, the pomade for which we PARASITIO FUNGI AND MOULDS. 65 subjoin the recipe has been very successful in pity- riasis, and in all the infantile forms of ringworm, including that which occurs in teething, and which may be safely treated, in spite of prejudices to the contrary : Turbith mineral (tri-mercuric sulphate)... 1 to 2 grs, Benzoinated lard aaa ae .. 15 grs. This pomade is lemon-coloured ; it will assume a flesh-colour by the addition of a few drops of red litmus, and may be scented to the taste of the person who is to make use of it. In ordinary cases of pityriasis, it need only be applied every eight or fifteen days. It is indispensable to wash the combs and brushes in a solution of potash or ammonia, lest the benefit of the treatment should be lost by re- infection. In the case of true ringworm, especially in adults, a much more energetic treatment is necessary, for which medical advice is required. 66 MICROBES, FERMENTS, AND MOULDS. CHAPTER II. FERMENTS AND ARTIFICIAL FERMENTATIONS. I. WHAT IS FERMENTATION ? CHEMISTS define fermentation in these words: “Fer- mentation takes place wherever an organic compound undergoes changes of composition, under the influence of a nitrogenous organic substance called a ferment, which acts in small quantities and yields nothing to the fermented substance” (A. Gautier). This nitrogenous substance, termed a ferment, is regarded by naturalists as an organized living being, either animal or vegetable. This was demonstrated by the researches of Cagnard de La Tour, of Turpin, of Dumas, and more recently by the splendid achieve- ments of Pasteur. It is now proved that the artificial fermentation which takes place in the manufacture of wine, beer, etc., is produced by small microscopic plants, called ferments or yeast. The chemical transformation resulting from them might be obtained without the intervention of yeast, FERMENTS AND ARTIFICIAL FERMENTATIONS. 67 properly so called, either by means of a nitrogenous substance of animal origin (Berthelot), or by other chemical and physical processes which we shall presently mention. But it may be questioned whether the nitrogenous substance of animal origin, which Berthelot considers to be dead, does not contain a living ferment. This is not admitted to be the case by Béchamp, whose theory will be given further on. Whenever fermentation is produced solely by the influence of physical and chemical agents, the action is very slow. But it is, on the other hand, very rapid when effected by living ferments or yeast, and it is also much less costly, so that”the latter mode of fermentation is preferred by manufacturers. Yeast is, therefore, the true agent in artificial fermentations. All the saccharine liquids which contain glucose or grape sugar, or a sugar which can be transformed into glucose, and also all nitrogenous substances, phos- phates, and ammoniacal salts, produce alcohol at a temperature varying between 25° and 100°, and the yeast of beer (of which the spores are carried through the air) appears and is developed at the same time; this occurs in the juice of grapes, beetroot, sugar- cane, ete. The alcoholic liquids thus produced are then subjected to distillation in order to extract the alcohol. The transformation of alcohol into vinegar is produced by another ferment. Fermentations are very common in nature. The transformation of sugar into lactic, butyric, and 68 MICROBES, FERMENTS, AND MOULDS. caproic acids, under the influence of nitrogenous substances and of the air; the change into glucose of gums, of starch, of dextrine, of sucrose, and mannite; the transformation of these substances into each other under the influence of living agents, or of those belonging to a living organism; the transformation of such glucosides as populin, salicin, tannin, etc., into sugar, or into neutral or acid substances ;—all these phenomena are fermentations (A. Gautier). We may even go further. The germination of seeds and the ripening of fruit are accompanied by phenomena of the same order. In animals, gastric, pancreatic, and intestinal digestion, together with other changes connected with nutrition and assimilation which take place in the blood and in all the organs, may be considered as true fermentations. In this case the cells of our tissues and the blood-corpuscles play the part of yeast in effecting alcoholic fermentations. Finally, the miasmatic, virulent, and contagious diseases, which we shall study in another chapter, are also caused by changes in the blood and in the other fluids of the system, and should be considered as fermentations, produced by minute microscopic organisms analogous to ferments, and which are, as we shall presently show, bacteria or microbes, strictly so-called, The putrefaction of dead bodies is also a fermentation. We shall, in this place, only consider the fermen- tations which are used in manufactures, FERMENTS AND ARTIFICIAL FERMENTATIONS. 69 History—tThe precise knowledge of the nature of fermentation is of comparatively recent date. The ancients, indeed, seem to have had an idea, however vague, of this phenomenon, which was in their case connected with the erroneous theory of spontaneous generation. We all know the fable of the bees, born from the putrefying body of a slain bull, which forms one of the chief episodes of the Metamorphoses of Ovid, and of the fourth book of Virgil’s Georgics. Aristotle says that, by means of heat, one living being may have its birth in the corruption of another. . . Fermentation is, in fact, always accompanied by an evolution of heat. The same idea was revived in the Middle Ages, and during the Renaissance by alchemists and physicians. Van Helmont, who lived early in the seventeenth century, goes so far as to say, “It is true that a ferment is sometimes so bold and enter- prising as to form a living being. In this way, lice, maggots, and bugs, our associates in misery, have their birth, either within our bodies or in our excrement. You need only close up a vessel full of wheat with a dirty shirt, and you will see rats engendered in it, the strange product of the smell of wheat and of the animal ferment attached to the shirt.” Beside these singularly rash and purely fanciful assertions, which show that imagination was allowed in those days to play a much too important part in natural science, we find a theory of the fermenta- 70 MICROBES, FERMENTS, AND MOULDS. tion in putrefying bodies which would not be rejected by modern naturalists and chemists. “ After death . . . the foreign ferments, which are always intent on change, are borne through the air and introduce corruption into dead matter... at least, unless the flesh is combined with certain sub- stances, such as sugar, honey, or salt. It is, therefore, these ferments, attacking whatever matter is deprived of life, which disintegrate and prepare it to receive a new soul (or fresh life).” Linnzeus, again, says that “a certain number of diseases result from animated, invisible particles, which are dispersed through the air... .” Boerhave, in 1693, distinguished three kinds of fermentation: alcoholic, acetous, and putrefactive. But we must come down to the beginning of this century in order to find more definite ideas respecting the organic nature of ferments, In 1813, a chemist called Astier asserted that every kind of germ from which ferments proceed is carried by the air; that this ferment, of animal nature, is alive, and is nourished at the expense of the sugar, and hence results disturbance of the equilibrium between the elements of sugar. Subsequently, in 1837, Cagnard de La Tour de- clared yeast to be a collection of globules which are multiplied by budding; and in the following year Turpin described the yeast of beer as a vegetable, microscopic organism, which he termed Torula cere- visicee (Fig. 35). FERMENTS AND ARTIFICIAL FERMENTATIONS. 71 Chemists were at first unwilling to admit the important part played by yeast in fermentations, and in order to explain it, they assumed the existence of a very obscure physico-chemical phenomenon, to which the name of catalysis, or action by presence, was given. But in 1843 an illus- trious French chemist, Dumas, gm clearly explained the physiological = oy function of the living ferment, or "Fons cores, eas eer (x 400 diam.), yeast. “Fermentations,” he writes, “are always pheno- mena of the same order as those which characterize the regular accomplishment of the acts of animal life. They take possession of complex, organic substances, and unmake them suddenly or by degrees, restoring them to the inorganic state. Several successive fer- mentations are, indeed, often required to produce the total effect. The ferment appears to be an organized being ; . . . the part played by the ferment is played by all animals, and by all but the green parts of plants. All these beings and organs consume organic substances, multiply and restore them to the simplest forms of inorganic chemistry.” Finally, Pasteur’s memorable labours, which he began to publish in 1857, confirmed the new theory of fermentation, which no one now doubts. Pasteur states that every fermentation has its specific ferment ; in all fermentations in which the presence of an or- 72 MICROBES, FERMENTS, AND MOULDS. ganized ferment has been ascertained, that ferment is necessary. This minute being produces the transforma- tion which constitutes fermentation by breathing the oxygen of the substance to be fermented, or by ap- propriating for an instant the whole substance, then destroying it by what may be termed the secretion of the fermented products. Three things’are necessary for the development of the ferment: nitrogen in a soluble condition, phosphoric acid, and a hydrocarbon capable of fermentation (such as grape sugar). Finally, every organized ferment of fermentation or putrefac- tion is borne about in the air, as may be shown by experiments. II. VEGETABLE NATURE OF FERMENTS OR YEAST. Yeast, or ferments, are in their organization closely allied to the fungi of which we spoke in the preceding chapter under the name of Microsporon. Many botanists still assign them to the class of fungi under the name of Saccharomycetes ; yet, as they live in liquids, or at any rate on damp substances, like the Algee, which are species of water-fungi, it is now almost agreed to place them in the same category as the latter, which they resemble in their whole organi- zation, except in the absence of chlorophyl. This last characteristic, the only one by which they ap- proximate to fungi, is common both to them and to ‘microbes or bacteria, which are only ferments of FERMENTS AND ARTIFICIAL FERMENTATIONS. 73 smaller size, and which are now also placed in the class of Algz. We shall return to this subject when we come to speak of bacteria. The structure of ferments is very simple: each plant is generally composed of a single cell, spherical, elliptical, or cylindrical, formed of a thin cell-wall, con- taining a granular substance called protoplasm, which is the essential part of the plant. These cells have an average diameter of ten micro-millimetres. They grow and bud, and when one of them reaches a certain size, a median constriction occurs; it divides into two parts, resembling the mother cell, and these some- times separate, sometimes remain united in a group or chaplet (Fig. 35). This mode of multiplication continues as long as the plant remains in a liquid favourable to its nutrition. But if its development is hindered, if, for example, the liquid dries up, the pro- toplasm contained in each cell contracts, and is transformed into one or more globules, which are the spores or endogenous reproductive organs of the plant. These spores may remain undeveloped for a long while, may become perfectly dry, and may even be subjected to a very high temperature, without losing the power of germination when they are again placed in conditions favourable to their development. They then reproduce the plant from which they had their birth, and are multiplied in the same manner.* * For further details on ferments and fermentations, see Schutzenberger’s work on the subject. 74 MICROBES, FERMENTS, AND MOULDS. III. Wine FERMENTS; ALCOHOLIC FERMENTATION. The commonest ferment of wine is, according to Pasteur, Saccharomyces ellipsoideus (Figs. 36, 37, 38), which must not be confounded with Kutzing’s Cryptococcus vini, since the latter has nothing to do Fig. 36.—Sacch ellipsoid wine ferment, in process of budding (x 600 diam.). with alcoholic fermentation. This ferment is found on the grape, and is thus introduced into the ferment- Fig. 37.—Sacch, ellipsordeus : Fig. 38.—Sacch. ellipsoideus : development of spores (x germinationof spores ( x 400 400 diam.). diam.). ing-vats. The adult cells are of an elliptic form, and are six micro-millimetres in length, by four or five in width. They bud, and are reproduced in the way already indicated, which is common to all ferments. FERMENTS AND ARTIFICIAL FERMENTATIONS. 75 Sacch. Pastorianus (Rees) is probably only a variety of the foregoing (Fig. 39), differing a little in the form of the cells, which are elongated, pyriform, or club-shaped. Lastly, Sacch. conglomeratus is somewhat rare. It is found in the grape-must when fermentation is nearly over (Fig. 40). It is so called because the new cells are conglomerated, instead of being arranged in a chaplet. We must now notice the other ferments which Fig. 39.—Sacch. Pastori- Fig. 40.—Sacch. conglom- Fig. 41.—Sacch. exiguus anus (x 400 diam.). eratus (x 600 diam.). (x 350 diam.). are found, like those given above, in fermented syrups, and which may also produce the alcoholic fermenta- tion of wine. Such is Sacch. exiguus (Fig. 41), of which the cells are much smaller than in the fore- going, since they are only three micro-millimetres by two and a half micro-millimetres. The apiculate ferment, of which Engel has made a separate genus, under the name of Carpozyma apiculata, is the alcoholic ferment which appears to be the most widely diffused in nature (Fig. 42). It is found on all kinds of fruit, especially upon berries and drupes, as well as upon most of the fruit-musts 76 MICROBES, FERMENTS, AND MOULDS. which are in process of fermentation. It has likewise been observed in Belgium upon beer. It is generally the first to appear and bud in the must. Its name is Fig. 42.—Sacch. apiculata (Carpozyma), g* of fruits (x 600 diam.). due to the characteristic form of its cells, which are formed like rape-seed, or apiculated at both extremi- ties of their large axis. In the fermented must of red wine we find, together with Sacch. ellipsoideus, a somewhat dif- ferent form, which is perhaps only a variety—Sacch. Reesit. We must also mention another alcoholic ferment, Sacch. mycoderma, wine or beer flowers, which con- 9 Q Ag “IN ‘ eae Ne A } ay \h Fig. 43.—Sacch. mycoderma, or hig. 44.—Different forms of Sacch. wine-flowers (x 350 diam.). mycoderma, stitute the white pellicle often seen on bottled wine (Figs. 43, 44). Pasteur has shown that, under certain FERMENTS AND ARTIFICIAL FERMENTATIONS. 77 circumstances, Mycoderma vini can produce alcoholic fermentation ; this is easily shown by adding it to a saccharine solution, in which it soon produces fermenta- tion. It appears on the surface of all alcoholic liquids which are exposed to the air, when fermentation is over or nearly over. Its growth is very rapid ; a few cells are enough to cover the surface in the course of forty-eight hours with a thin white or yellow pel- licle, which is at first smooth, and then wrinkled. This implies, according to Engel’s estimate, that a single cell has produced 35,000 others in this short time. Most of these different forms are probably only different stages of development of a limited number of species, since ferments are as polymorphic as microscopic fungi. We have said that before they are found in the must of wine or fruits, the ferments fasten in a dormant state on the epidermis of the fruit, by which means they are introduced into the liquid about to be fermented. We see how the spores are transported through the air until they rest on the downy surface of a drupe or berry. But it has been asked what becomes of this ferment between last year’s vintage and the succeeding summer, and in what way it passes the winter. According to Hansen’s researches, Sacch. apiculata, which is, for instance, found upon gooseberries, is washed off them by the rain, dispersed by the wind, and falls to the ground with the fruit, where it 78 MICROBES, FERMENTS, AND MOULDS. remains buried through the winter as a dormant spore, in order to return to the same fruit when it has ripened in summer. It can only be borne through the air when the ground is completely dried. In the same way, the ferments of wine, after having passed through the bodies of men and animals, pass the winter on the dungheap. This revelation may not be pleasing to drunkards, but it will not surprise those who are acquainted with the habits of cryptogams in general, and of fungi in particular. Brefeld has found these ferments during the winter, especially in the excrement of herbivorous animals, and on the dungheap. The manufacture of wine is too well known to require description ; we need only remind our readers that alcoholic fermentation essentially consists in the transformation of glucose, or grape-sugar, into alcohol and carbonic acid. The latter, given off in the form of gas, produces the ebullition or effervescence which characterizes fermentation, and to which its name is due. Sugar or glucose is, therefore, the essential nutriment of all yeast-plants, and the indispensable element of these fermentations, of cider, beer, and all fermented liquors, as well as of wine. IV. Brerr-YEAst, The yeast of beer, or Sacch. cerevisiw, was the earliest known and the most carefully observed of FERMENTS AND ARTIFICIAL FERMENTATIONS. 79 all the ferments, and may be regarded as the type of the family. Its cells are round or oval, from eight to nine micro-millimetres in their longest diameter, isolated or united in pairs (Fig. 35). When these cells are-deposited in a saccharine liquid, which is therefore susceptible to fermentation, vesicular swellings, filled with protoplasm at the expense of the mother cell, may be observed at one Fig. 45.—Yeast of superior beer Fig. 46.—Spores of beer-yeast, in budding (x 400 diam.). different phases of development. or two parts of the surface of the cell; these swellings increase, acquire the size of the mother cell, and then contract at their base (Fig. 45). They generally arise on the sides of the cell, more rarely on its extremities. The new cells thus formed soon separate from the mother cell, and the protoplasm given up to its off- spring by the latter is replaced by one or two empty spaces, termed vacuoles. When yeast is not in a liquid susceptible to fermentation, it can remain for a longer or shorter time without modification. If abruptly deprived of all nutriment, and especially of sugar, and placed in a sufficiently moist atmosphere, 80 MICROBES, FERMENTS, AND MOULDS. spores may be produced (Fig. 46). It is rather difficult to perform the experiment with success ; the ferment must be frequently washed with distilled water, as it may otherwise putrefy, instead of fruc- tifying (Schutzenberger). Let us briefly describe the process by which the fermented liquor termed beer is obtained. The barley which constitutes its essential principle does not contain sugar; but when it has germinated it contains a substance termed diastase, under the influence of which the starch of barley can be converted into glucose. The barley, which has been moistened in order to make it swell and germinate, is spread in a thin layer on hurdles, at a temperature of about 15°: this opera- tion is called malting. It is generally performed in spring, in order to ensure the necessary warmth and moisture, and March beer is considered the best. When the sprout attains to two-thirds of the length of the grain, germination is arrested by drying the grains on a stove, and they are then ground to powder and become malt. This malt is then steeped in water at the temperature of 60° and by the action of the diastase the starch becomes glucose. This saccharine fluid or wort is boiled with hops, which are now added, not only to give a bitter and aromatic taste, but also to preserve it. This infusion of malt and hops is concentrated and cooled, and beer- yeast, the product of previous operations, is added in FERMENTS AND ARTIFICIAL FERMENTATIONS. 81 order to establish fermentation. The yeast is procured by collecting the scum of fermented beer and straining it into bags. In Belgium, the wort is allowed to stand until the spontaneous development of fermentation takes place ; but in France and Germany the ferment is generally added. In this case two methods are in use, fermenta- tion from above, and fermentation from below ; and this enables us to distinguish two kinds of yeast, that of superior, and that of inferior beer (Figs. 45, 47). In superior beer, the saccharifica- tion of the starch of malt is effected by successive steepings in casks at the relatively high temperature of from 15° to 18°. As the yeast is pip. 47 yeast of in- formed, it gradually issues from the — éf budding (2400 bung-holes in the upper part of the taste cask ; hence its name. In England, large open vats are used: the yeast rises to the top, and is removed with skimmers. In the manufacture of inferior beer, saccharifica- tion is effected by steeping the malt in open vats at the lower temperature of from 12° to 14°. The yeast is deposited at the bottom of the vats in a doughy and tenacious mass. When the first and most active fermentation is at an end, the clear liquid is drawn off and put into casks, bottles, or pitchers, and as the separation of the yeast is not yet complete, 5 82 MICROBES, FERMENTS, AND MOULDS. it continues to act on the unmodified sugar. The production of fresh yeast makes the liquor thick, and the amount of alcohol and of carbonic acid increases in accordance with the time for which it is kept, after being bottled or put in closed casks. The manufacture of most fermented liquors resembles that of wine or beer; that of cider is-very simple, and consequently approximates to the manu- facture of wine. The apples are cut and crushed, and remain in the vats until fermentation is over; the liquid is then separated from the solid residue, and put into casks or bottles. V. CONCERNING SOME OTHER FERMENTED Liquors. There are many other fermented liquors made in various countries with substances derived from the animal or vegetable kingdom. In France, cider or perry is sometimes made from pears or crab-apples. What the French call boissons are cheap fermented liquors, prepared from dried raisins or aromatic sub- stances, such as the dried fruit of the coriander, to which water sweetened with treacle is added. Fer- mentation is usually effected by germs borne by the air, or by those introduced by the coriander and the other ingredients of the liquor ; or it may be hastened, as in Belgian beer, by the addition of beer-yeast or baker’s yeast. It is effected by the transformation of FERMENTS AND ARTIFICIAL FERMENTATIONS. 83 the sugar into alcohol and carbonic acid, and this con- stitutes an aérated drink, which is very agreeable when well made, and especially if it has been carefully bottled before fermentation is over. Kowmiss is made of soured and fermented mare’s milk, and is much used in Russia as a refreshing drink, from which an alcoholic liquor may be distilled. Many kinds of brandy are made from the fruits and seeds of different plants. Kirschwasser is the alcohol produced by distilling cherries or geans; rum is made from sugar-cane, arrack from rice. Gin, distilled from the juniper-berry, is largely consumed by the labouring classes in England, as corn-brandy is in the French drinking-shops. The savage Malay and Polynesian races prepare fermented liquors from the sap of various plants. Such is kava, made from masticated roots, and steeped in an infusion of Piper methysticum. In this case, the ptzalin, a ferment contained in the human saliva, transforms the fecula into a sugar susceptible to fermentation. The operators sit round a large vessel containing the roots steeped in water, and each man takes a piece, which he masticates conscientiously until it is sufficiently impregnated with the salivary ferment. This process is revolting to our ideas, and few Europeans would touch a liquor which has been prepared in such a way; but this is doubtless an educated prejudice which would not occur to a native of Oceana. 84 MICROBES, FERMENTS, AND MOULDS. The dragon-trees (Dracena terminalis and D. Australis) also possess a feculent root, from which a fermented liquor is extracted in the same manner by the Sandwich Islanders, VI. Tsar LEAVEN oF BREAD. Bread is leavened in order to make it porous and more digestible. According to Engel, the microbe of baker’s yeast is Sacch. minor, resembling that of beer- yeast, only more minute. Most of the yeasts which we have examined contain a great variety of microbes. However this may be, the fermentation of bread, like other fermentations, sets free carbonic acid gas, and this raises the dough and makes it light. * CHAPTER III. MICROBES, STRICTLY SO CALLED, OR BACTERIA. JI. THE VEGETABLE NATURE OF MICROBES. As we have seen in the preceding chapter, there is no well-defined limit between ferments and bacteria, any more than between ferments and fungi, or, again, between fungi and bacteria. Their smaller size is the principal difference which separates bacteria from ferments, since in other respects these two classes are for the most part alike in form and organization. There are bacteria of large size, such as Leptothrix buccalis, so frequently found in the mouth even of a healthy man, which much resembles in its mode of growth some of the lower fungi, such as Oidiwm albicans. Yet the latter is regarded as a fungus, and the former as an alga, by our best eryptogamous botanists. It may, however, be said that the two classes of algz and fungi are connected with each other by their lower forms, and probably. have a common origin ; just as the two great organic kingdoms are connected by their 86 MICROBES, FERMENTS, AND MOULDS. lower forms, which have been by some united in the kingdom Protista. Microbes, or bacteria (Schizophyta or Schizomycetes), appear, in liquids examined under the microscope, as small cells of a spherical, oval, or cylindrical shape, sometimes detached, sometimes united in pairs, or in articulated chains and chaplets (Fig. eg 48). The diameter of the largest of these of oe cells is two micro-millimetres, and that > a of the smallest is a fourth of that size, ig aie Heaeng 8° that at least 500 of the former and amet Cie ~=©2000 of the latter must be placed end font hems of to end in order to attain the length of ed orn haps amillimetre. Itis therefore plain that a ce aaa magnifying power of 500 to 1000 dia- meters, or even still higher, is required to make these beings clearly visible under the microscope. One very common bacterium may be found every- where, and can be easily procured for microscopic observation: Bacteriwm termo, or the microbe of im- pure water. This bacterium is not injurious to health, since there is no potable water in which it is not found in greater or less quantity. In order to obtain numerous specimens, it is enough to take half a glass of ordinary water from a spring or river, and to leave it for some days on a table or chimney-piece, the vessel being uncovered to allow the access of air. We may soon observe that a thin coating is formed on the surface of the water, which looks like a deposit MICROBES, OR BACTERIA. 87 of fine dust; this dust consists of myriads of bacteria. If we take a drop of this water and place it under a cover-glass, in order to examine it under a micro- scope with a magnifying power of about 500 dia- meters, we shall, as soon as the instrument is properly focussed, see a really surprising spectacle. The whole field of the microscope is in motion; hundreds of bacteria, resembling minute transparent worms, are swimming in every direction with an un- c d x b @ e 15S ‘ f ba 7; te, ! wf Ory Sele, Ss “ey . r) 4 fy € nad Fa, 64 / oats ° \2 ie ia are), f eas % Ff) ak, 8 Y ® 4 e 8 \ Fig. 49.—Bact. termo in different stages of development, a-h (much magnitied ), dulatory motion like that of an eel or snake. Some are detached, others united in pairs, others in chains or chaplets or cylindrical rods which are partitioned or articulated (Fig. 49); these are only less mature or younger than the first. Finally, we see a multitude of small globules which result from the rupture of the chaplets. All these forms represent the different transformations of Bacteriwm termo, or the microbe of 88 MICROBES, FERMENTS, AND MOULDS. putrefaction. Those which are dead appear as small, rigid, and immovable rods. In observing the lively movements of these minute organisms, we might be tempted to regard them as animals. But we know that movement, taken by itself, is not peculiar to the animal kingdom. Setting aside the movement which can be provoked in the mimosa and in many higher plants, it is well to remember that many of the lower plants are capable of motion: this is the case with Diatomacee, in which the presence of chlorophyl incontestably proves their vegetable nature. The spores of plants of a much higher organization, such as ferns and mosses, lave the power of swimming in the water, just as bacteria have: this has procured for them the name of Zvospores, although many of them contain chlorophyl. The movements of bacteria are, like those of zoo- spores, due to the presence of vibrating cilia, which are inserted at both extremities, or only at the hinder extremity of the microbe, and which form organs of propulsion analogous to the tails of tadpoles. These organs are very transparent and are difficult to see in the living subject, even with the strongest magnifying power, on account of the rapidity of their movements. But their existence has been ascertained by the use of staining fluids, and above all by micro-photography. If, however, we analyze the mode of motion in Bacterium termo, and compare it with the movements of the ciliated or flagellated infusoria which may often MICROBES, OR BACTERIA. 89 be seen swimming with it in the field of the microscope, we are struck by the difference. Infusoria come and go, swiftly or slowly—they go back or move to the right or left; in a word, their movements seem to be actuated in some sense by will. Nothing like this is observed in the bacterium. The undulatory move- ment by which it is animated is always the same, and impels it straightforward, like a stone sent from a sling; it never voluntarily goes back nor out of its course, but only under the influence of a foreign im- pulse, such as contact with another bacterium, when it rebounds, just as a projectile may rebound from a wall. On encountering an obstacle, the bacterium remains indefinitely undulating before it, without ever pausing or showing signs of fatigue, until some external cause comes to release and send it to the right or left. We may often see a tangled mass of bacteria, perhaps adhering by their cilia or by some other substance, in which all the individuals continue to undulate until the rupture of the mass permits them to depart in all directions. These organisms are therefore plants in the character of their movements, as well as in the rest of their organization. In bacteria each cell consists of a cellulose wall, containing protoplasm, as we saw was the case in fer- ments. The multiplication by fission is effected in precisely the same way in bacteria and ferments, and so also is the formation of spores. Under certain circumstances, when the liquid on which they subsist 90 MICROBES, FERMENTS, AND MOULDS. is dried up, the protoplasm contracts and forms spores, which, when set at liberty by the rupture of the cell- wall, germinate and give birth to fresh bacteria. The only difference consists in the fact that ferments may produce several spores in each cell, while bacteria never produce more than one. Bacteria were, as we have already said, for a long ~ while classed with fungi under the name Schizomycetes. But recent researches into their organization, and more especially into their mode of reproduction, show that they resemble a group of inferior alge termed Phy- cochromycee, which includes Oscillaria, Nostocs, and Chroococcus, species generally furnished with chloro- phyl. Bacteria represent a similar group devoid of chlorophyl. Zopf, in a treatise recently published, goes still further: he asserts that the same species of alga may at one time be presented in the form of a plant living freely in water or damp ground by means of chlorophyllaceous protoplasm, and at another in the form of a bacterium or parasitic microbe, devoid of chlorophyl, and nourished at the expense of organic substances which have been previously elaborated by animals or plants, thus accommodating itself, accord- ing to circumstances, to two very different modes of existence, MICROBES, OR BACTERIA. 91 II. CLASSIFICATION OF MICROBES, OR BACTERIA. It is very difficult to make any natural classifica- tion of the organisms which belong to the group of microbes; we have, in fact, seen that they only differ from each other in external form, and that these forms are very variable, since the same organism may present itself successively as an isolated globule, a chaplet, a chain, and a more or less articulated rod. Microbes are essentially polymorphous, and adapt themselves to varied conditions of existence, which influence the form taken by these microscopic organisms. For this reason their classification has often varied, their dis- tinction into genera and species does not yet rely on precise data, and the opinions formed by various authors in accordance with their personal researches still differ widely. We will, however, subjoin Wunsche’s classification. Schizophyta, or Schizomycetes. A. Division of cells always occurring in the same direc- tion, so as to form a chaplet before the joints or members separate. 1. Cells united in mucilaginous or gelatinous families. a. Cells united (in a state of repose) in amorphous families, a. Spherical or elliptic cells, colourless and gene- rally motionless ... oes eee ove Micrococcus. B. Cells elongated in short, movable itis oe Bacterium. b. Cells united in families with sharp outlines, lobu- lated and agglutinated like frog-spawn ... Ascococcus. 2. Cells arranged in filaments. 92 MICROBES, FERMENTS, AND MOULDS. a. Cylindrical filaments, indistinctly articulated, mo- tionless. a. Unramified, very slender filaments: (1) Short... ao ave eee eee «. Bacillus. (2) Long ... dae Po aes oc ... Leptothrix. B. Filaments repeatedly bifurcated (false ramifi- cations) sis eae oes wee ws. Cladothrix. b. Spiral, movable filaments: Q) Short, faintly undulated sae ose ... Sptrochete. (2) Long, flexible ... oe oo oes w» Vibrio. (3) Short, rigid... eee vee oes -. Spirillum. _(4) Rolled into mucilaginous mass wes ... Myconostoc B. Cells dividing cross-wise, and the daughter cells re- maining united, like packets tied with a crossed cord see nee tee wee Saaretnae. Most of the microbes of which we have now to speak may be assigned to one or other of the genera given in this scientific enumeration, and sometimes, on account of their polymorphism, to several of these genera. Before making a more detailed study of some of them, it may be interesting to glance at them as a whole, following the order of classification given above. The genus Micrococcus (Hallier) includes the spherical microbes, which are the most common and the most widely diffused, probably because the spores and early stages of all the other forms Pe ’ < stp, have this spherical shape before be- : ere coming elongated and assuming their o 3p e adult form (Fig. 50). ae This genus is divided into two der the form Mi- : . 5 erococeus (much enw SeCtions: the first includes Micro- larged). . ° . ) coccus chromogenis, %.e. fabricators of colouring matter—an extremely interesting group, on MICROBES, OR BACTERIA. 93 which we must say a few words, since these microbes play an important part in nature, connected with hygiene and domestic economy; the second section includes Micrococcus pathogenis, or the producers of disease, which must detain us longer. The genus Bacterium, of which the name indicates that it is rod-shaped, also includes some coloured species and more which are colourless, such as the bacteria of putrefaction, of stagnant waters, of vegetable infusions, ete. (Fig. 49). The genus Ascococcus is less common. The cells, united in groups or families, form mucilaginous, wrinkled membranes on the surface of putrefying liquids, on the juice of meat, on the infusion of hay, ete. Bacillus (or Bacteridiw, Davaine) forms an ex- tremely important genus, characterized by its long, flexible, and articulated filaments ; this genus includes the butyric ferment, and the microbe which produces the disease called anthraa, or splenic fever. Leptothria buccalis is found in the human saliva and between the teeth (Fig. 51, &). Cladothria dichotoma forms a kind of fine grass, which appears like a whitish mucilage on the surface of putrefying liquids (Fig. 51, p). ‘Vibrio rugula and V. serpens are found in infusions in the form of tolerably thick filaments, which have only one inflection, while their successors are spirally curved (Fig. 51, /). 94 MICROBES, FERMENTS, AND MOULDS. Spirillum and Spirochete only differ from each other in the number and approximation of their spirals. Spirochete Obermeieri is found in the blood of those affected by recurrent fever; S. plicatile, which is found in stagnant water, amid Oscillaria, is Fig. 51.—Different forms of microbes, or bacteria: a, b,c, d@, Micrococcus of various forms; e, the short Bacterium; f, the short Bacillus; k, Leptothrixz or long bacillus: 1, Vibrio, dividing by fission; m, Spirillum; 0, Sptrochete; p, Clado- thria, etc. (from Zopf: highly magnified). perhaps only the parasitic form of those alge, and has often been regarded as the cause of marsh fever. Spirillwm is also found in infusions (Fig. 51, m, 0). Finally, Sarcina ventriculi, so different in form from other microbes, is found in the fluids of the human stomach, in the blood, and in the lungs, in the MICROBES, OR BACTERIA. 95 form of yellow patches. It is also found in the albu- men of boiled eggs, in potatoes, ete. (Fig. 52). a ae Fig. 52.—Sarcina ventriculi, in different degrees of development (strongly magnified). III. THe MicroBe oF VINEGAR, AND ACETIC FERMENTATION. Pasteur has shown that the acid fermentation of alcoholic liquids is due to the existence of a special microbe, acting like a ferment, which is developed on the surface of fermented liquors whenever they are abandoned to the contact of the air, in the presence of - albuminoid substances. ‘This microbe, which consti- tutes the mother of vinegar, and which is termed Mycoderma, aceti, is probably identical with Bacteriwm lineola, so often present in infusions, in stagnant pools, and even in spring water. It is a true bacterium (Fig. 48). The membrane which may be observed on the surface of liquids in course of acetic fermentation is formed of very minute elongated cells, from 1°5 to 3 micro-millimetres in length, united in the form of 96 MICROBES, FERMENTS, AND MOULDS. chains or curved rods. They multiply by the trans- verse fission of the cell, a fission preceded by a median constriction. These are characteristics of the bac- terium, strictly so called. The nutrition of this microbe resembles that ot beer-yeast: it requires mineral salts, phosphates of the alkaline metals and of the metals of the alkaline earths, proteid matters, or ammoniacal salts. This ferment is an oxidizing ferment, which with- draws oxygen from the air and transfers it to the alcohol, thus converting it into acetic acid; hence it can only subsist in contact with the air, and perishes when it is submerged, so that acetification is then arrested. The oxidizing power of this microbe is such that it can even oxidize alcohol and transform it into carbonic acid gas—a fact which explains how the strength of wine is lowered by the other and larger species, Mycoderma vini, of which we have given an illustration (Figs. 43, 44). This action is less lively in the presence of a considerable quantity of vinegar, and at Orleans acetification is always effected in vats which contain a large amount. What is called the Orleans process, which is the one generally employed in France, consists in filling tuns which can hold about 200 litres with 100 litres of vinegar and 10 litres of white or red wine; once a week 10 litres of vinegar are drawn off, and replaced by 10 litres of wine. The temperature should be about 30°. Oxygen is supplied by a proper system of MICROBES, OR BACTERIA. 97 ventilation. This process is somewhat slow, since it only produces ten litres of vinegar out of each tun in the course of the week, and it has the disadvantage of encouraging the multiplication of anguillide, the small nematoid worms which live in vinegar and sour paste. : Pasteur has modified and improved the original process so as to obviate both inconveniences. He employs heat, which allows the process of acetification to be intermittent, and thus prevents the development of the anguillide. Shallow vats, about 30 centi- metres in depth, with lids in which holes have been pierced, are used, and mycoderma is scattered on their surface. Gutta-percha tubes, pierced with holes at their lower extremity, are placed at the bottom of these vats, so that fresh liquid can be added without disturbing the superficial film of mycoderma. In Germany, vinegar is made by means of spongy platinum, or platinum black, which oxidizes alcohol without the intervention of a microbe. This affords a good example of fermentation, or of an analogous phenomenon, produced solely by physico-chemical action. The platinum black acts by disintegrating the alcohol and placing it in more intimate contact with the oxgyen of the air, since the process of oxidation would be much slower without either this process or the presence of the ferment. 98 MICROBES, FERMENTS, AND MOULDS. IV. THe MICROBES WHICH AFFECT WINE. The affections to which some wines are subject alter their taste and quality so as often to render them unfit for use. These affections ought to be recognized, so that a diseased wine may not be con- founded with one which is adulterated, and it is by means of the microscope that we are enabled to recognize the nature of these changes. Chaptal for- merly ascribed them to the presence of an excess of ferment, since he was unable to discover’ any other cause. We now know from Pasteur’s valuable re- searches, published in his book, Etudes sur les vins, that they are all due to the presence of microbes peculiar to each disease. “The source of the diseases which affect wine,” Pasteur writes, “consists in the presence of parasitic microscopic plants, which are found in wine under conditions favourable to its development, and which change its nature either by the withdrawal of what they take for their own nutriment, or still more by the formation of fresh products which are due to the multiplication of these parasites in the wine.” These diseases are known under the names of acescence, pousse, graisse, amertume, ete. We shall review them in succession. Mouldy or Flowered Wine.—These are wines on the surface of which white pellicles are formed (fleurs de vin), which consist of Mycoderma vini (Figs. 43, 53). MICROBES, OR BACTERIA. 99 This product does not turn the wine sour, nor sensibly affect it. It is due to the temperature of the casks being too high during the hot season. It may be obviated by sprinkling them with cold water, or by putting ice into them; care must also be taken to keep the casks full, and the cellars as cool as possible. Acidity of Wines; Soured Wines.—Wine always Fig. 53.—The disease acescence, which sours wine. Deposit seen in the microscope; 1, 1, Mycoderma vini ; 2,2, Mucoderma aceti, still young; 3, the same older, when the mischief is at an advanced stage. contains a small quantity of acetic acid, and when this acid is in excess, the wine is no longer drinkable, and turns to vinegar. This change is due to the presence of Mycoderma aceti (Fig. 53), of which we have already spoken. It is much more minute than M. vini, and takes the form of the figure 8, as the illustration shows, or of chaplets formed by the union 100 MICROBES, FERMENTS, AND MOULDS. of several 8’s placed end to end. As they grow older, the two globules of the 8 divide, and appear as isolated granules. These two species of Mycoderma are in- compatible, and are never found in the same wine. The acid may be isolated by distilling the sour wine. The attempt has been made to cure or im- prove sour wine by adding normal potassium tartrate (from 200 to 400 grammes to every hogshead of 230 litres), which forms potassium acetate and bitartrate by neutralizing the excess of acid. The bitartrate is deposited spontaneously, and crystallizes. Carbonate of lime cannot be employed for the same purpose, since it would spoil the wine. Wines that are turned or over-fermented (vins poussés ; vins bleus).—This disease displays the follow- ing characters: the wine assumes a bluish or brown colour, and becomes turbid; if shaken in a test-tube, we may observe silky waves floating in every direction. When a cask is tapped, the wine spurts up, and it is said “qui a la pousse.” If poured into a glass, a number of minute bubbles appear on the surface, the discolouration increases, and the wine becomes more turbid. The taste is changed and becomes insipid, as if water had been added. The disease is developed in very hot weather (Chevalier and Baudrimont). This affection is due to the presence of an ex- tremely attenuated microbe, somewhat resembling that of lactic acid, which we shall describe presently, MICROBES, OR BACTERIA. 101 but differing from the latter in its undivided filaments. Its diameter is at the most one micro-millimetre : it varies in length, and is flexible, in which it resembles the genus Vibrio. These filaments collect in a mucous deposit at the bottom of the cask (Fig. 54). Wine undergoes successive changes under the in- fluence of this pathogenic ferment, and this has led Fig. 54.—Wines affected by pousse. Deposit seen under the microscope: 1, ordinary alcoholic wine-ferment ; 2, acicular crystals of potassium bitartrate ; 3, crystals of normal calcium tartrate; 4, Vibrio, or microbe which produces the disease, to the belief that there are several distinct diseases; hence the different names which have been given to this affection. The remedies for the disease consist in the ad- dition of tartaric acid; in drawing off the wine into sulphured casks, and adding a little brandy; and in taking care to keep the cellars whitewashed and airy. 102 MICROBES, FERMENTS, AND MOULDS. Wine affected by Ropiness.—White wines, and especially champagne, are more often affected by this disease than red wines. It is more apt to attack wine which has little alcohol and is deficient in tannin, and under its influence the liquor becomes turbid, flat, and insipid, ropy, like white of egg, and it loses its sugar. This change is effected by a filamentous microbe, Fig. 55.—Disease of ropiness in wine, affecting champagne, and caused by a bacterium which assumes two forms: the figure 8, and chaplets. even more like the lactic ferment (Fig. 58) than the one we have just described, since it is likewise formed of very minute globules, united in chaplets, which are, however, more attenuated than those of the lactic ferment. These filaments form a species of feltwork through which the liquid slowly filters; hence its oily appearance. It is probably a bacterium (Fig. 55). MICROBES, OR BACTERIA. 103 This ferment may be destroyed by tannin (15 grammes to a hogshead), which has the effect of pre- cipitating it. Very ripe sorbs, which have been crushed, may also be used for this purpose, as well as gall- nuts and grape-seeds which have been ground to powder ; all substances rich in tannin. The precipitate thus formed should be separated from the wine by refining. Wines affected by Bitterness.—This disease affects red wines, especially those of the choicest vintages of Burgundy. Pasteur writes that “at its outset the wine assumes a peculiar smell, its colour is less vivid, and its taste becomes insipid. Soon the wine becomes bitter, and there is a slight taste of fermen- tation, due to the presence of carbonic acid gas. Finally, the disease becomes more aggravated, the colouring matter is completely changed, and the wine is no longer drinkable.” ~ The microbe which is the essential cause of this disease is seen under the microscope in the form of articulated filaments, curled back or bent, and it may, or may not, be invested with the colouring matter of the wine. It is reproduced by fission, not by bud- ding. It is probably a bacillus (Fig. 56). This ferment must not be confounded with that of wine affected by pousse, of which the filaments are much moreslender, the articulations are hardly apparent, and they are not incrusted with colouring matter, Pousse is readily developed in wines of inferior quality, 104 MICROBES, FERMENTS, AND MOULDS. while the finer sorts are more often attacked by bitterness, The bitterness may be to some extent neutralized by the addition of new and sweet wines, but the application of lime (from 25 to 50 centigrammes the Fig. 56.—Bitter disease of wine. Deposit under the micr pe: 1, 2, fil ts of the microbe (Bacillus) which produces the disease, mixed with crystals of tartar and colouring matter (Bordeaux wine); 3, young microbes in an active state; 4, dead microbes, incrusted with colouring matter. litre) is more recommended. This treatment must, however, make the wine sour. The deposits formed in deteriorating or old wines are not effected by the microbes which we have just enumerated, but are due, according to Pasteur, to the combination of oxygen with the wine under the action of time. This constitutes the aging of wine. Viscous Fermentation of Saccharine Liquids— What is termed viscous fermentation takes place in the MICROBES, OR BACTERIA. 105 juice of beetroots, carrots, and onions, and in liquids containing sugar and nitrogenous substances. It is probably produced by the same ferment which causes the ropiness of wine (Fig. 55), and the liquid assumes a viscous or oily appearance. Pasteur states that this microbe acts on the glucose and transforms it into gum or dextrine, into mannite and carbonic acid. The lactic and butyric fermenta- tions, which are often simultaneously produced in saccharine liquids, are due to distinct microbes. V. THE Microbe or Lactic FERMENTATION. The sugar contained in milk, as well as grape sugar, can be transformed into lactic acid. This transformation is always caused by the presence of a ferment with which Pasteur has made us ac- quainted. It had been previously supposed that milk turned sour spontaneously when it was allowed to stand for some days. In this case, as we know, the milk curdles, and the clear liquid which separates from the curd is called whey. In 1780, Scheele, the celebrated Swedish chemist, extracted lactic acid from whey. The same acid is also found in sour-crout; in the sour water of starch; in baker's yeast; in water in which peas, beans, or rice have been boiled, and then suffered to ferment; and, finally, in the juice of beet- root which has passed through viscous and alcoholic 6 106 MICROBES, FERMENTS, AND MOULDS. fermentation, after which it turns sour and produces lactic acid and mannite. Lactic fermentation requires the presence of pro- teid matters in process of decomposition, and it can only be carried on when the degree of acidity in the liquid does not exceed definite limits. For this purpose a certain amount of chalk is added, to neutralize the acid formed at the expense of the sugar. It is somewhat difficult to observe the microbe of this fermentation without previous instruction. It appears in the form of grey patches, which are readily confounded with casein, and with the disintegrated gluten, or the chalk of the liquid under examination. Os alk Fig. 57.—Lactic ferment in Fig. 58.—Lactic ferment chuplet (Schutzeuberger). (Pasteur). Under the microscope the patch is seen to consist of minute globules, or of filaments with very short articu- lations, isolated or in flakes. These are the characters of the genus Bacteriwm (Figs. 57, 58). The globules are much more minute than those of the yeast of beer, and are strongly agitated when in isolation by a motion incorrectly termed Brownian movement; and which does not in reality differ from the movements which may be observed in most of the spores of the lower orders of plants, and in a great number of bacteria. MICROBES, OR BACTERIA. 107 This ferment is often found in wine, together with those of yeast and alcohol, and produces in it an in- cipient lactic fermentation. The predominance of one of these fermentations depends on the composition of the medium, which may be more or less adapted to them. A slightly alkaline medium is most suitable for the lactic microbe, while in a perfectly neutral medium only alcoholic fermentation will occur. We have already said that mare’s milk can be transformed into an alcoholic liquid called koumiss. VI. Tar AMMONIACAL FERMENTATION OF URINE. Shortly after its discharge, urine which is left to itself assumes an ammoniacal odour. This is due to the transformation of the urea (the nitrogenous principle of urine) into ammonia and carbonic acid, under the influence of a microbe which appears in the form of free globules, of articulated filaments (Torula), or of chaplets, resembling those of the lactic ferment. This microbe is found in the white deposit which collects at the bottom of vessels, and has been termed Micrococcus wree (Fig. 59). This ferment is conveyed through the air, like other microbes of fermentation. It does not exist in the bladder as long as the urine remains acid. Yet, in the rare cases in which urine has been found to be alkaline, immediately after its issue from the bladder, 108 § MICROBES, FERMENTS, AND MOULDS. it may be ascertained that the ferment was introduced by some accidental cause, such as a surgical examina- tion, and that the sound served to convey the microbe. It is, in any case, sufficiently common at the exterior orifice of the urethra, and at the depth of two or three centimetres, Von Tieghem has shown by precise experiments ocae a & eo 8 } ato 4 rg Big ec % 8 oo) 8g e weieeds * © 259 FF om g & oe ey ® % & for) Fig. 59.—Micrococcus uree (Von Tieghem). Microbe of ammontacal fermentation. It may be observed that the bacterium is in the figure 8, or in chaplets. (Much magnified.) that the presence of this microbe is the true cause of the ammoniacal fermentation of urine. With certain precautions, the urine withdrawn from a healthy bladder may be preserved for an indefinite time, These experiments have been recently resumed by Sternberg, an American physician, who hag clearly demonstrated that only the microbes of the air, or MICROBES, OR BACTERIA. 109 those of the orifice of the urethra, can produce this fermentation. Since the latter are always carried off by the first discharge of urine, only the second por- tions of the emitted liquid should be collected in a perfectly clear vessel, which has been sterilized, or, carefully freed from all atmospheric germs. The vessel should then be put under a glass shade to protect it from these germs, and if all proper pre- cautions are taken, the urine will remain clear and acid for an indefinite time without undergoing am- moniacal fermentation. If afterwards a little plug of amianthus, which has been previously sterilized by heat, should be introduced by a small pair of pincers into the urethra to a depth of two centi- metres, and then dropped into this untransformed urine, it will soon be transformed, and undergo am- moniacal fermentation. But if the plug of amianthus has been steeped in an antiseptic solution (diluted carbolic acid) before being introduced into the urethra, it will not produce this fermentation, VIL. Buryric FERMENTATION OF BUTTER, CHEESE, AND MILK. Butyric fermentation follows lactic fermentation in milk, butter, and cheese, and it is butyric acid which gives to butter its rancid taste. This fermentation also occurs in saccharine substances, and generally in all proteid substances, 110 MICROBES, FERMENTS, AND MOULDS. Pasteur has ascertained that this fermentation results from the development of a microbe which takes the form of minute cylindrical rods, rounded at their extremities, usually straight, and either isolated or united in chains of two or more articulations. These rods are about two micro-millimetres in width, and from two to twenty micro-millimetres in length. They advance with a gliding motion, are often curved, and present slight undulations. They are reproduced by fission. These characters are those of the genus bacillus. Coagulation of Milk: Cheese.—The coagulation of milk is artificially produced by rennet, the liquid secreted in a calf’s stomach. Human gastric juice produces the same effect, and the milk introduced as an aliment into the stomach is never digested until it has been curdled, both in children and adults. The artichoke flower, and other plants of the genus Car- dwus, will also curdle milk at a temperature between SS 30° and 50°. It is probable that this we a action is due to the presence of an ‘N organized ferment (animal or vege- Figen, Bacilus amy. table cells), which here supplies the cus), butyric ferment, Place of the microbe of lactic fermen- tenofcheese. tation, It is with rennet, or with the still more active liquid produced by the maceration of the testicle of an unweaned calf, that those cheeses are made which consist only of curd, boiled or unboiled, fresh or fer- MICROBES, OR BACTERIA. 111 mented, and obtained from the milk of cows, sheep, or goats, skimmed or unskimmed, according to the kind of cheese desired, Sweet-milk cheese do not differ in their composi- tion from those of curdled milk. They consist of casein, albuminoid matter which encloses particles of butter: the liquid residue is the serum or whey, which con- tains lactic acid and mineral salts. Cheese, strictly so called, such as Gruyeére and Roquefort, only differ from the foregoing because they have been exposed for a shorter or longer time to the action of the air, and of the microbes suspended in it. Cheese is first oxidized under the influence of the oxygen of the air; butyric and even alcoholic fermen- tation soon follows lactic fermentation, together with the disengagement of hydrogen and of putrid pro- ducts, when the action of the ferments which effect these transformations has gone on too long. In order to obtain the different kinds of cheese which come into the market, they are exposed to the weather, generally in holes which have been excavated in the rock for this purpose, on a bed of straw, or sometimes partially covered with it, until the cheese is ripe and has attained the desired quality. Butyric and ammoniacal fermentations lead us directly to the study of putrefaction; that is, the fer- mentation of dead organic matter. 112 MICROBES, FERMENTS, AND MOULDS, VIII Purreracrion, OR THE FERMENTATION OF DEAD ORGANIC MaTTER; A GAME FLAVOUR. The flesh of animals used for food is said to be high in the first stage of alteration which occurs when it is left to itself. Pasteur does not believe that this effect is produced’ by the intervention of the ferments of the air, although this is the case with the putrefac- tion which follows. He thinks that it merely results from the action of what are called soluble or natural ferments in the serum of the meat, and that there is a chemical, reciprocal reaction of the liquids and solids which are withdrawn from the normal action of vital nutrition. This explanation is adapted to satisfy those epicures who have a taste for high game and not for microbes. Yet it is certain that this condition passes into true putrefaction without any abrupt transition, and we knowthat immediately after death the microbes, which penetrate everywhere, take possession of the animal tissues and begin their work of destruction. When flesh is high, it is therefore probable that it is in the first stage of putrefaction. Gautier has made some experiments on the sub- ject, and holds that this condition is certainly due to the action of microbes, and consequently to germs in the air. In fact, meat which is placed in a soldered and air-tight case after it has been deprived of germs by a suitable process, is devoid of any high odour at MICROBES, OR BACTERIA. 118 the end of six months, and is as fit for food as freshly killed meat. However this may be, meat which is high is usually not injurious, while putrefied meat produces diarrhoea or still more serious illness. Davaine has shown that the septic properties of decomposed blood are not removed by subjecting it to a temperature of 100°, which destroys the microbes, but not their germs or spores; for the destruction of the latter a still higher temperature is necessary. For a long while it was believed that the putrefac- tion of dead bodies, and of albuminoid substances, either animal or vegetable, which have been exposed to a moist air at a temperature of from 15° to 30°, was merely due to the instability of the organic compounds; these, when left to themselves, tend, under the influence of oxygen, to produce more stable compounds by dis- integration and successive oxidations. Pasteur has, however, shown that in this case also there is a true fermentation; that is, a decomposition produced by the vital action of certain microbes. In general, when organic animal substances are exposed to the air, they are in the first instance rapidly covered with moulds; they lose their co- herence, and after the lapse of a few days give off fetid effluvia. Carbonic acid, nitrogen, hydrogen, carburetted, sulphuretted, and phosphoretted hydro- gens, are freely disengaged, and at the same time they combine with the oxygen of the air. The microbes, 114 MICROBES, FERMENTS, AND MOULDS. which appear simultaneously with the moulds, pene- trate deeply into the tissues, disintegrate them by feeding at their expense, and the putrid condition increases ; then the decomposition changes its nature and becomes Jess intense. The putrefied matter is finally desiccated, and leaves a brown mass—a complex mixture of substances combined with water (hydro- carbons), and of fatty and mineral substances which gradually disappear by slow oxidation (Gautier). Pasteur has ascertained, from the microscopic \) cme Oi} g Wf aad iE Uo thea Be 2 ealii« “9 Fig. 61.—Bacilli of pu- A irefaction (Rosenbach : much magnified ) Fig. 62.—Zoogtoea of Spirillum tenue. study of the phenomena which occur in an infusion of animal matter in process of decomposition, that microbes appear in it in the form of globules or short rods (Micrococcus, Bacterium termo, Bacillus, etc.), which are either free or collected in a semi- mucilaginous mass, to which the special name zoogloea was at first given (Fig. 62). These microbes rapidly deprive the liquid of all its oxygen. At the same time a thin layer of mucedinew and of bacteria is MICROBES, OR BACTERIA. 115 found on the surface, which also absorb this gas and do not allow it to penetrate into the lower part of the liquid. This liquid now becomes the seat of two very distinct actions. In its interior, vibriones succeed to the free globules and zoogloea, of which they appear to be only a higher stage of transformation. These microbes multiply and change the albuminoid matter into more simple substances; insoluble cellulose, fatty bodies, and gaseous putrid matters. Meanwhile, the microbes on the surface actively consume the products thus developed, transforming them into carbonic acid, nitrogen, and the oxides of nitrogen, etc. This ex- plains why, when there is an insufficiency of oxygen, putrefaction may indeed begin; but it languishes, and is finally arrested. The cause of the fetid odours which escape from putrefying bodies and liquids is not well understood. It may be ascribed to the disengaged gases (carburetted, phosphoretted and sulphuretted hydrogen, and ammo- niacal compounds), and to the circulation of decom- posing organic particles. We also find formic, acetic, lactic, butyric, valerianic, and caproic acids, generally combined with ammonia, and the fatty acids which are one result of the successive disintegrations of albuminoid matters. When these gases are disengaged, a substance remains which may be compared with humus, or vegetable earth. It is rich in fats, in earthy and 116 MICROBES, FERMENTS, AND MOULDS. ammoniacal salts, and consequently constitutes a strong manure, very fit to serve as the nutriment of plants. This is at once the beginning and the termination of the endless chain which sustains the equilibrium of nature, in which there is no creation, no destruction. Plants draw their nutriment from the soil and the air in the form of mineral solutions, and are devoured by animals or by other parasites; animals are in their turn devoured by microscopic plants or microbes, and return by means of putrefaction to the condition of mineral salts, which are distributed in the soil, and serve anew for the nutrition of plants. We must at the same time be struck by the resemblance which exists between these phenomena of putrid fermentation, and those which occur in the fermentations which accompany the nutrition of animals and plants. Germination and the different digestions which occur in the mouth, the stomach, the intestines, ete, are only fermentations, so that Mitscherlich has paraphrased the Scripture saying, “Dust thou art, and unto dust thou shalt return,” by declaring that “ Life is only a corruption.” It should, however, be remembered that fermenta- tions are essentially phenomena of disintegration, which always reduce complex, organic substances to those which are simpler. Plants provided with chlorophyl, on the other hand, alone possess the property of forming higher organic compounds, by MICROBES, OR BACTERIA. 117 the aid of purely inorganic substances. Animals and plants devoid of chlorophyl get their nutriment by unmaking the complex substances elaborated by the green parts of plants, and these act in the same way for their own profit in those organs which have no chlorophyl ; as, for instance, in the seed and embryo. * IX.—AROBIES AND ANAEROBIES. We have seen that microbes, at different epochs of their existence, and in accordance with the nature of their environment, can assume very diverse forms, Thus the organism, which at first appears in the form of globules (micrococcus), either isolated or united in more or less numerous colonies by a kind of muci- laginous envelope (Zoogloea), when it again becomes free, may be elongated in the shape of the figure 8, which is formed of two cells about to separate; or a Jarge number may be included in the form of a straight, articulated rod (Bacteriwm), or in a rod which is curved, waved, or even spiral (Vibrio, Spirillum, Spirochete), always more or less mobile; or, again, the cells may form long, stationary filaments (Bacillus), ete. So also the habitat and mode of life divide the microbes into very distinct classes. Some can only subsist when they breathe the natural oxygen they withdraw from the atmosphere; they can only exist 118 MICROBES, FERMENTS, AND MOULDS. on the surface of liquids, or of the organic substances on which they feed. These are termed aérobies, or consumers of air. Others, again, can live beneath the surface of liquids and in living organisms, or of those in process of decomposition, and must neces- sarily derive the oxygen necessary for their respira- tion from the oxygenated substances in which they are found. These are termed anaérobies. Fig. 63.— Vibrio rugula in different stages of development (anaérobie), much enlarged. XN ry This distinction and the theory on which it relies have been introduced into science by Pasteur, and they appear to be founded on observed facts. Thus Bacterium termo, which lives on the surface of putre- fying liquids, is an aérobie; while Vibrio rugula (Fig. 63), which lives below the surface of the liquid, below the layer formed by the Bacterium termo, is an anaérobie, and derives its oxygen from the water or solid matters which are found in it in suspension or solution, and even from other microbes. So, again, the yeast of superior beer is an aérobie, and the yeast of inferior beer is an anaérobie, etc. Paul Bert regards MICROBES, OR BACTERIA. 119 the corpuscles of the blood, and the cells of which all our tissues consist, as true anaérobic microbes; so likewise are the microbes which, when introduced into the blood, are the cause of certain diseases. The important consequences of this fact, which it is neces- sary to note, will appear presently. X.—TueE Microses oF SULPHUROUS WATERS. The formation of the sulphurous springs which are so numerous in the Pyrenees and in other parts of France, appears to be due to the presence of small alge of the family Oscil- latoria, and of the genera S288 SEES ES Ba Oscillaria and Beggiatoa (Fig. 64). These microbes are of the same structure as those of which we have spoken above, but they contain chlorophyl, and also a blue colouring matter. They are placed in the group Cyanophycece, which, as Zopf believes, contains species that are sometimes green, and sometimes colourless, like Bacillus and Leptothrix, which they resemble in their mode of reproduction. According to Louis Ollivier, these alge reduce the sulphates of waters charged with sulphate of lime, transforming them into sulphur. They even accumu- late sulphur in their celis. When sulphur is thus Fig. 64.—Beggiatoa alba, wicrobe of sulphurous springs. 120 MICROBES, FERMENTS, AND MOULDS. abundantly supplied to them, the microbes are very mobile; as soon as the quantity of sulphur diminishes they become less mobile, and reconsume the sulphur they have stored up; finally, they become quite motionless—a phenomenon concomitant with the forma- tion of spores. Within each cell of the filamentous alga there is a minute sphere, brilliant and refracting, of which the development is in inverse ratio to the quantity of sulphur in the surrounding liquid. These spores become free in the form of chaplets, after the destruction of the cell-wall, and these chaplets are precisely like those of Bacillus subtilis. Planchud was the first to whom it occurred to look for a special ferment in the glairine or barégine which may be seen floating on the surface of sul- phurous waters. He showed that one gramme of car- bolic acid to a litre of water arrests the reduction of the sulphates into sulphur, and that this reduction is resumed as soon as the carbolic acid has evaporated. Six grammes to the litre completely destroy the Sulphuraria, as these alge are termed by Planchud. This observer also performed experiments which led him to believe that the same alge will reduce gypsum to native sulphur, and that the vast deposits of sulphur found in certain regions are due to the action of this microscopic plant. It is now well known that a chemical action of the same nature, the production of saltpetre, is the work of similar microbes. MICROBES, OR BACTERIA. 121 XI. THE MicROBES WHICH PRODUCE SALTPETRE. It is known that nitre or saltpetre, 7.e. potas- sium nitrate, is produced in damp places where de- composing animal matter is found in contact with carbonate of potassium, It is found, cembined with other salts of lime, soda and magnesia, in stables, sheep- folds, cellars, in the neighbourhood of urinals, and in the earth of some localities (Peru and Chili). Its industrial importance in the manufacture of gun- powder, etc, has led to its collection. Formerly it was extracted from the plaster of old houses, or from artificial nitre works which combined conditions favourable to its production. Nitrates are produced by the gradual oxidation of the ammonia furnished by animal exoretions. For a long while it was supposed that this oxidation was simply due to the influence of porous bodies, such as earth and stone walls. Nitric acid was produced, then nitrates of lime, potas- sium, ete. The rescarches of Boussingault, Schloesing, and others, have now taught us that this phenomenon of organic chemistry is due, like many others, to the vital activity of one or more species of microbe, whose invariable presence in the natural or artificial nitre-works has been ascertained. These microbes are aérobies, i.e. they only live and work when in contact with the oxygen of the air, from which they derive 122 MICROBES, FERMENTS, AND MOULDS. materials for effecting oxidation. This is another instance of the part played by microbes in artificial fermentation. Gayon and Dupetit believe that, in addition to the microbes which produce nitre, there are others which decompose the nitrates produced by the former. When nitrate of potassium is placed in culture- liquids, drain-water, chicken-broth, etc. it disappears rapidly under the action of these microbes. Under favourable conditions of temperature and environ- ment, culture microbes daily reduce one gramme of nitre to the litre. This decomposition causes the dis- engagement of nitrogen, the formation of ammonia and carbonic acid, which latter remain in solution in the form of bicarbonate. Gayon and Dupetit believe that this fact explains certain chemical phenomena which occur in the soil, under the influence of manure and water. Thus fresh discoveries show more clearly every day the importance of the part played by microbes in nature. Agriculture, manufactures, geology, and chemistry must take them into account, since they are the active agents of a number of phenomena which have hitherto been obscure in physics, chemistry, and physiology. MICROBES, OR BACTERIA. 123 XII. Tue Microses wHicH DESTROY BUILDING MATERIALS. The observations of Parize, director of the agronomic station, Morlaix, lead to the belief that microbes, which destroy dead bodies and effect such various transformations in nature, not only attack the beams of our houses, as we have already seen, but building materials of an imorganic nature, including stones. On one occasion, when Parize was examining some mucedinecee which had vegetated on a brick partition, in a closed and somewhat damp recess, he noticed blisters on the coat of plaster. He broke one of these blisters, and a fine red dust, consisting of pulverized brick, issued from it. When placed in the micro- scope, under a magnifying power of about 300 diameters, he saw, amid schistoid fragments, dia- tomatacez and silicious algze pertaining to the original clay of the bricks, an immense number of living microbes: micrococcus, bacteria, amcebe, and ciliated spores of algae, moving rapidly in the drop of water used to moisten the dust. Some of these were in process of budding. These organisms existed under a coat of five to six mm. of plaster, and even of 30 mm. at the bottom of a hole pierced by the brace; but in this case they were less numerous, in the proportion of two to three. The germs and spores which exist 124 MICROBES, FERMENTS, AND MOULDS. both in air and water may, therefore, be indefinitely preserved in a protective medium, such as a brick wall covered with plaster. They are nourished at the expense of the ammoniacal salts which are found in the air in a gaseous state, and which are fixed by atmospheric moisture, and it is probable that they derive little nutriment from the solid materials in thé midst of which they live, although by their increase disintegration may ensue. Hence, especially from the hygienic point of view, it is so important to disinfect the walls of hospitals, barracks, stables, etc., by scraping and whitewashing them. Parize also believes that microbes may perform a geological part in nature by disintegrating the schistoid rocks which enter into the constitution of arable soil. But we are now speaking of microbes of recent origin, since the temperature to which clay is subjected in order to make red bricks would certainly destroy all the microbes and their germs. This is not the case with the microbes of chalk, which, according to Béchamp, are of very ancient origin. XIII. Tort Micropes oF CHALK AND COAL. Béchamp’s researches tend to show that microbes, which he calls microzyma, or small ferments, have an almost indefinite term of life. We know that chalk consists almost entirely of the remains of the calcareous MICROBES, OR BACTERIA. 125 shell of Rhizopoda, protozoaria or microscopic animals which lived in incalculable numbers in the seas of the secondary period, and which still live at the bottom of oceans. Béchamp holds that the organic substance of these rhizopoda, or of the microbes which live in their midst, has retained its vitality in the mass of chalk, since a freshly cut piece, taken from the quarry with all possible precautions to exclude air-germs, is able to furnish microbes which multiply rapidly in a favourable medium, and produce various fermenta- tions. We have already seen that bacteria germs resist. desiccation, heat, and all kinds of destructive influences, and remain for a long while, even for several years, in the condition of dormant spores; but the existence of spores of the same kind in chalk of the secondary period indicates a still more sur- prising vitality. It is not, however, inexplicable if we suppose that these microbes pass through successive periods of activity and repose, and if we compare these facts with those presented by the microbes of saltpetre, of mineral waters, and of the anaérobic microbes, which are able to live when deprived of the oxygen of the air. Béchamp was the first to observe the presence of granulations in coal, which appear under the micro- scope to be microbes. These microbes must be far more ancient than those of chalk, but they have lost all vitality ; it has been found impossible to develop them in infusions, and to obtain fermentations from 126 MICROBES, FERMENTS, AND MOULDS. them. But this cannot always have been the case, and it has been supposed that the phenomenon of coal formations, still so obscure and so variously explained, was, at any rate, partially due to the physiological labour of these microbes, and con- sequently belongs to the class of fermentations. XIV. Cuoromocrenic MICROBES. In addition to the colourless microbes, such as are most of those we have hitherto considered, there are others remarkable for their vivid and varied colours, which betray their existence to the least practised eyes. Many of these microbes attack our alimentary substances, and should therefore be known to the manufacturer and hygienist, since their action on the human system is often injurious. Many phenomena which have struck the imagina- tion of ignorant and credulous people are merely due to the presence of these coloured microbes. In 1819, a peasant of Liguara, near Padua, was terrified by the sight of blood-stains scattered over some polenta, which had been made and shut up in a cupboard on the previous evening. Next day similar patches appeared on the bread, meat, and other articles of food in the same cupboard. It was naturally regarded as a miracle and warning from heaven, until the case had been submitted to a Paduan naturalist, who easily MICROBES, OR BACTERIA. 127 ascertained the presence of a microscopic plant, which Ehremberg likewise found at Berlin in analogous cir- cumstances, and which he named Monas prodigiosa. At that time all microbes were confounded in the Monad genus; we now term it Micrococcus pro- digiosus. It has been observed not only on bread, but on the Host, on milk, paste, and on all alimentary or farinaceous substances exposed to damp heat. This microbe has been recently studied by Raben- horst, who declares that it is polymorphic, and has received a number of different names: Palmella miri- fea, Zoogalactina vmetropha, Bacterium prodigiosum, which are only varieties of Micrococcus prodigiosus, modified by the medium in which it is nourished. This observer noticed its appearance on cooked meat kept in a cellar. The spherical cells, examined under the microscope, were shown to be filled with a reddish oil, which gave them a peach-blossom tint, and when transferred to raw meat they assumed a splendid fuchsia colour, resembling spots of blood. This plant is only developed in the dark, and the nitrogen necessary for its nutrition must be derived from the air, especially when it is developed on bread, the Host, ete., in which nitrogen is deficient. When it is said to rain blood, this phenomenon is | likewise due to the presence of a minute plant, prob- ably similar to that which often gives a red tint to ponds and reservoirs in autumn. This microscopic alga appears to be the one discovered by Ehremberg in 128 MICROBES, FERMENTS, AND MOULDS. 1836, in a stream near Jena, and which he named Ophi- domonas jenensis, or sanguinea (Fig. 65). It is, on account of its form, now placed in the genus Spirillum. Like many other plants, it readily passes from green to red. No one is surprised by the green scum which covers reservoirs in summer, since it is so common; but when this colour changes, often in a single night, and passes from green to red, the unaccus- tomed tint excites wonder, although it is caused by Fig. 65.—Ophidomonas sanguinca of Fig. 66.—Protococcus nivalis of stagnant water (slighily magnified). red snow (magnified). the same plant which was green the day before. If there is a thunderstorm or waterspout which draws up the red water from the ponds and reservoirs, and discharges it in the form of rain on the surrounding “country, we hear of the phenomenon that it rains blood, and it would be easy to find in the drops of rain the reddish microbe which imparts this colour to them. In northern regions the snow is often tinged with the colour of blood by an analogous Micrococcus, which - MICROBES, OR BACTERIA, 129 presents the same transition from green to red (Fig. 66). Green-tinted. snow may be found adjacent to the red snow, and under the microscope it displays minute green globules, identical, except in colour, with those of the red-tinted snow, The variety of colour in these microbes is extreme. Micrococcus awrantiacus gives an orange colour to Fig. 67. terium cy microbe of blue milk (Neelsen). It is probable that several different forms are here contused under this name. B, zoogloea, bread and eggs; M. chlorinus is grass-green ; MM. cyanus is of a beautiful azure blue; M. violaceus is violet or lilac, and WM. fulvus is rust-coloured. These have all been observed on food. M. candidus forms little white patches upon cheese. The genus Bacterium also furnishes its contingent of coloured species; such are B. aanthinum and 7 130 MICROBES, FERMENTS, AND MOULDS. B. cyanogenum, which give respectively a yellow or blue colour to milk (Fig. 67). Peasants say that an evil eye has been cast upon the milk, but it is easy to prove that the development of these microbes is due to imperfect cleansing of the tin milk-vessels, since the discolouration ceases when greater care is taken to wash and scald the vessels. Bread often displays microscopic growths of a dark green or orange colour, and in this state it cannot be introduced into the stomach without danger. In the first case it is Bacteriwm crugi- nosum, in the second Micrococcus awrantiacus. The badly made and badly baked bread of the French peasants, which is often kept for a fortnight or more, exposed to the moisture and heat which favour the development of these microbes, sometimes displays the first of these changes; the second is particularly common in soldiers’ bread, which must likewise be baked several days in advance, and which is conveyed in carts exposed to the weather. Mégnin recently observed a cryptogamic growth of this kind on the bread distributed to the garrison of Vincennes. The spores of these microbes are found in flour, and resist a temperature of 120°, while they are destroyed by that of 140°. Thus they are no longer found in the crust, of which the temperature rises to 200°; but may easily subsist in the much lower temperature of the crumb. Hence the necessity of only using flour perfectly free from germs. MICROBES, OR BACTERIA. 131 The pus of wounds is often coloured blue by an aérobic micrococcus, of which the protoplasm is colourless, but which makes a colouring matter called pyocyanine, and this gives a blue tint to the lint and bandages used for dressing the wound. 2 XV. THE Microse oF BALDNESS. In addition to the numerous parasitic fungi of skin on which the hair grows thickly, which we have already noticed, the human hair is attacked by a true microbe, which is, according to the re- searches of Gruby, Malassez and Thin, the cause of Alopecia areata, one form of baldness. The parasite has the appearance of a micrococcus, and penetrates the interior of the hair, which is, as we know, hollow. The hair must be made transparent by potash, in order to see the microbe. It probably penetrates between the bulb and the hair-follicle as far as the root, is introduced into the hair, and multiplies and gradually rises higher in it, until the substance is disorganized. This microbe has been called Bacterium decalvans. 132 MICROBES, FERMENTS, AND MOULDS. CHAPTER IV. MICROBES OF THE DISEASES OF OUR DOMESTIC ANIMALS. I. ANTHRAX, OR SPLENIC FEVER. Tae first of the virulent and contagious diseases in which the presence of a microbe was positively ascertained was anthrax, or splenic fever, which attacks most of our horned animals, and especially cattle and sheep. As early as 1850, Davaine had observed the presence of minute rods in the blood of animals which died of splenic fever; but it was only in 1863, after Pasteur’s first researches into the part played by microbes in fermentations, that Davaine suspected these rods of being the actual cause of the disease. He inoculated healthy animals with the tainted blood, and thus ascertained that even a very minute dose would produce a fatal attack of the disease, and the rods, to which he gave the name of Bacteridia, could always be discovered in enormous numbers in th blood. ANTHRAX. 133 The microbe so named by Davaine must from its characteristics be assigned to the genus Bacillus, and is now termed Bacillus anthracis. This disease, which affects men as well as animals, is characterized by general depression, by redness and congestion of the eyes, by short and irregular respiration, and by the formation of abscesses, which feature, in the case of the human subject, has procured for it the name of malignant pustule. The disease is quickly terminated ig. 68.—Bacillus anthracis of splenic fever in different stages of development: sa bacilli, spores, and curled filaments (much enlarged). by death, and an autopsy shows that the blood is black, that intestinal hemorrhage has occurred, and that the spleen is abnormally large, heavy,and gorged with blood; hence the name of splenic fever. The disease is generally inoculated by the bite of flies which have settled upon carcases and absorbed the bacteria, or by blood-poisoning through some accidental scratch, and this is especially the case with knackers 1384 MICROBES, FERMENTS, AND MOULDS. and butchers who break and handle the bones of animals which have died of anthrax. The period of incubation is very short. An ox which has been at work may return to the stall apparently healthy. He eats as usual; then lies down on his side and breathes heavily, while the eyes are still clear. Suddenly his head drops, his body grows cold; at the end of an hour the eye becomes glazed ; the animal struggles to get up, and falls dead. In this case, the illness has only lasted for an hour and a half (Empis). ‘Rig. 69.—Bacillus anthracis, produced in guinea-pig by inoculation: corpuscles of : blood and bacilli. In order to prove that the disease is really caused by Bacillus anthracis, Pasteur inserted a very small drop of blood, taken from an animal which had recently died of anthrax, in a glass flask which con- tained an infusion of yeast, neutralized by potassium and previously sterilized. In twenty-four hours the liquid, which had been clear, was seen to be full of very light flakes, produced by masses of bacilli, readily ANTHRAX. 135 discernible under the microscope. A drop from the first flask produced the same effect in a second, and from that to a third, and soon, By this means the organism was completely freed from all which was foreign to it in the original blood, since it is calculated that after from eight to ten of such processes, the drop of blood was diluted in a volume of liquid greater than the volume of the earth. Yet the tenth, twentieth, and even the fiftieth infusion would, when a drop was inserted under the skin of a sheep, procure its death by splenic fever, with the same symptoms as those produced by the original drop of blood. The bacillus is, therefore, the sole cause of the disease. These cultures have often since been repeated by numerous observers, so that the microbe has been studied in all its forms, and the extent of its poly- morphism has been ascertained. At the end of two days the bacterium, which, while still in the blood, is of a short, abrupt form, displays excessively long filaments, which are sometimes rolled up like a coil of string. In about a week many of the filaments contain refracting, somewhat elongated nuclei. These nuclei presently form chaplets, in consequence of the rupture of the cell-wall of the rod which gave birth to them; others, again, float in the liquid in the form of isolated globules. These nuclei are the spores or germs of the microbes, which germinate when placed in the infusion, become elongated, and reproduce fresh bacilli, 136 MICROBES, FERMENTS, AND MOULDS. These spores are much more tenacious of life than the microbes themselves. The latter perish in a tempe- rature of 60°, by desiccation, in a vacuum, in carbonic acid, aleohol, and compressed oxygen. The spores on the other hand, resist desiccation, so that they can float in the air in the form of dust. They also resist a temperature of from 90° to 95°, and the effects of a vacuum, of carbonic acid, of alcohol, and compressed oxygen. In 1873, Pasteur, aided by Chamberland and Roux, carried on some experiments on a farm near Chartres, in order to discover why this disease is so common in some districts, in which its spread cannot be ascribed to the bite of flies. Grass, on which the germs of bacteridia had been placed, was given to the sheep. A certain number of them died of splenic fever. The glands and tissues of the back of the throat were very much swelled, as if the inoculation had occurred in the upper part of the alimentary canal, and by means of slight wounds on the surface of the mucous membrane of the mouth. In order to verify the fact, the grass given to the sheep was mixed with thistles and bearded ears of wheat and barley, or other prickly matter, and in consequence the mortality was sensibly increased. In cases of spontaneous disease it was surmised that the germs which were artificially introduced into food in the course of these experiments, are found upon the grass, especially in the neighbourhood of ANTHRAX. 137 places in which infected animals had been buried. It was, in fact, ascertained that these germs existed above and around the infected carcases, and that they were absent at a certain distance from their burial- place. It is true that putrid fermentation destroys most of the bacteria, but before this occurs a certain number of microbes are dispersed by the gas dis- engaged from the carcase; these dry up and produce germs, which retain their vitality in the soil for a long while. The mechanism by means of which these germs are brought to the surface of the soil and on to the grass on which the sheep feed is at once simple and remarkable. Earth-worms prefer soils which are rich in humus or decomposing organic substance, and seek their food round the carcase. They swallow the earth containing the germs of which we have spoken, which they deposit on the surface of the soil, after it has traversed their intestinal canals, in the little heaps with which we are all acquainted. The germs do not lose their virulence in their passage through the worms’ intestines, and if the sheep swallow them together with the grass on which they browse, they may contract the disease. The turning-up of the soil by the spade or plough may produce the same effect. A certain warmth is necessary for the formation of germs; none are produced when it falls below 12°, and the carcases buried in winter are therefore less dangerous than those buried in the spring and sum- 1388 MICROBES, FERMENTS, AND MOULDS. mer. It is, in fact, in hot weather that the disease is most prevalent. Animals may, however, contract it even in their stalls from eating dry fodder on which germs of these bacteria remain. Pasteur and his pupils performed an experiment in the Jura in 1879, which clearly shows that the presence of germs above the trenches in which car- cases have been buried is the principal cause of inoculation. Twenty oxen or cows had perished, and several of them were buried in trenches in a meadow where the presence of these germs was ascertained. Three of the graves were surrounded by a fence, within which four sheep were placed. Other sheep were folded within a few yards of the former, but in places where no infected animals had been buried. At the end of three days, three of the sheep folded above the graves had died of splenic fever, while those excluded from them continued to be healthy. This result speaks for itself. Malignant pustule, which is simply splenic fever, affects shepherds, butchers, and tanners, who handle the flesh and hide of tainted animals. Inoculation with the bacillus almost always occurs in consequence of a wound or scratch on the hands or face. In Ger- many, fatal cases of anthrax have been observed, in which the disease has been introduced through the mouth or lungs, as in the case of the sheep observed by Pasteur.. The human subject appears, however, to be less apt to contract the disease than herbivora, ANTHRAX. 139 since the flesh of animals affected by splenic fever, and only killed when the microbe is fully developed in the blood, is often eaten in farmhouses. In this case the custom prevalent among French peasants of eating over-cooked meat constitutes the chief safeguard, since the bacteria and their germs are thus destroyed. II. VaccInaTION FoR ANTHRAX. The rapidity with which anthrax is propagated by inoculation generally renders all kinds of treat- ment useless; if, however, the wound through which the microbe is introduced can be discovered, it should be cauterized at once. This method is often successful in man. The pustule is cauterized with red-hot iron, or with bichloride of mercury and thymic acid, two powerful antiseptics, certain to destroy the bacteridium. It is expedient, as an hygienic measure, to burn the tainted carcases, and if this is not done, they should be buried at a much greater depth than is usually the case. But the preservative means on which chief re- liance is now placed is vaccination with the virus of anthrax. Pasteur has ascertained that when animals are inoculated with a liquid containing bac- teridia of which the virulence has been attenuated by culture carried as far as the tenth generation, or even further, their lives: are preserved. They take 140 MICROBES, FERMENTS, AND MOULDS. the disease, but generally in a very mild form, and it is an important result of this treatment that they are henceforward safe from a fresh attack of the disease ; in a word, they are vaccinated against anthrax. In the cultures prepared with the view of attenu- ating the microbe, it is the action of the oxygen of the air which renders the bacteridium less virulent. It should be subjected to a temperature of from 42° to 43° in the case of Bacillus anthracis, to enable it to multiply, and at the same time to check the pro- duction of spores which might make the liquid too powerful. At the end of the week, the culture, which at first killed the whole of ten sheep, killed only four or five out of ten. In ten or twelve days it ceased to kill any; the disease was perfectly mild, as in the case of the human vaccinia, of which we shall speak presently. After the bacteridia have been attenuated, they can be cultivated in the lower temperature of from 30° to 35°, and only produce spores of the same attenuated strength as the filaments which form them (Chamberland). The vaccine thus obtained in Pasteur’s laboratory is now distributed throughout the world, and has already saved numerous flocks from almost certain destruction. Although this process has only been known for a few years, its results are such that the gain to agriculture already amounts to many thousands of pounds. Toussaint makes use of a slightly different mode ANTHRAX. 141 of preparing a vaccine virus, which is, however, analogous to that of Pasteur. He subjects the lymph of the blood of .a diseased animal to a temperature of 50°, and thus transforms it into vaccine. Toussaint considers the high temperature to be the principal agent of attenuation, and ascribes little or no im- portance to the action of the oxygen in the air. Chamberland and Roux have recently made re- searches with the object of obtaining a similar vaccine by attenuating the primitive virus by means of antiseptic substances. They have ascertained that a solution of carbolic acid of one part in six hundred destroys the microbes of anthrax, while they can live and flourish in a solution of one part in nine hundred, but without producing: spores, and their virulence is attenuated... When a nourishing broth is added to a solution of one in six hundred, the microbe can live and grow in it for months. Since the chief condition of attenuation consists in the absence of spores, this condition seems to be realized by the culture in a solution of carbolic acid, one in nine hundred, and it is probable that a fresh form of attenuated virus may thus be obtained. Diluted sulphuric acid gives analogous results. However this may be, the vaccine prepared by Pasteur’s process is the only one which has been largely used, and which has afforded certain results to cattle-breeders. Public experiments, performed before commis- 142 MICROBES, FERMENTS, AND MOULDS. sions composed of most competent men, have clearly shown the virtue of the protective action. In the summer of 1881, the initiation was taken by the Melun Society of Agriculture. Twenty-five sheep and eight cows or oxen were vaccinated at Pouilly-le-Fort, and then re-inoculated with blood from animals which had recently died of anthrax, together with twenty- five sheep and five cows which had not been previously vaccinated. None of the vaccinated animals suffered while the twenty-five test sheep died within forty- eight hours, and the five cows were so ill that the veterinary surgeons despaired of them for several days. This experiment was publicly repeated in Sep- tember, 1881, by Thuillier, Pasteur’s fellow-worker, whose death we have recently had to deplore, before the representatives of the Austro-Hungarian Government ; and again near Berlin, in 1882, before the representa- tives of the German Government, and always with the same success. Up to April, 1882, more than 130,000 sheep and 2000 oxen or cows had been vac- cinated ; and since that time the demand for vaccine from Pasteur’s laboratory has reached him from every quarter. III. Fown CHouera, The sickness of barn-door poultry, which is. com- monly called cholera, is caused by the presence in the OTHER DISEASES OF DOMESTIC ANIMALS. 143 blood of a small micrococcus or bacterium in the form of the figure 8, differing, therefore, in form from Bacil- lus anthracis, but also an aérobie. It may be cultivated in chicken-broth, neutralized by potash, while it soon dies in the extract of yeast, which is so well adapted to Bacillus anthracis. The microbe of this disease may also be attenuated by culture, and it may be done more easily than in the case of anthrax, since it is not necessary to raise the temperature, as the bacterium of fowl-cholera does not produce spores under culture. Pasteur has there- fore been able to prepare an attenuated virus well adapted to protect fowls from further attacks of this disease. IV. SwinE FEVER. The disease affecting swine, which is called rouget, or swine fever, in the south of France, has been recently studied by Detmers in the United States, where it is also very prevalent, and by Pasteur in the department of Vaucluse. It is a kind of pneumo- enteritis. These observers consider that the disease is caused by a very slender microbe, formed, like that of fowl- cholera, in the shape of the figure 8, but more minute. Others say that there is a bacillus which was observed by Klein as early as 1878 in swine attacked by this disease. In spite of the apparent contradiction, it is 144 MICROBES, FERMENTS, AND MOULDS. probable that we have only two forms of the same microbe, for the bacillus in Klein’s culture at first resembles Bacteriwm termo, in the form of an 8, before it is elongated into rods. Pasteur has succeeded in making cultures of microbes in the figure 8, He has inoculated swine with the attenuated form, after which they have been Fig. 70.—Swine fever: section of a lymphatic gland, showing a blood-vessel filled with microbes (much enlarged: Klein). able to resist the disease, so there is reason to hope that in the near future this new vaccine, containing the attenuated microbe, may become the safeguard of our pig-sties. V. OF SOME OTHER DISEASES PECULIAR TO DOMESTIC ANIMALS, An epidemic which raged in Paris in 1881 was called the typhoid fever of horses, and was fatal to more than 1500 animals belonging to the General Om- nibus Company in that city. This disease is also pro- OTHER DISEASES OF DOMESTIC ANIMALS. 145 duced by a microbe, with which Pasteur was able to inoculate other animals (rabbits); for this purpose he made use of the serous discharge from the horses’ nostrils. The inoculated rabbits died with all the symptoms and lesions characteristic of the disease. The attenuation of this microbe by culture is difficult, since at the end of a certain time the action of the air kills it. Pasteur has, however, found an expedient by which to accomplish his purpose. When the culture is shown to be sterile in consequence of the death of the microbe, he takes as the mother culture of a fresh series of daily cultures the one which was made on the day preceding the death of the first mother culture. In this way he has obtained an attenuated virus with which to inoculate rabbits, and the same result might undoubtedly be obtained in the case of horses. There are many other contagious diseases which affect domestic animals, and which are probably due to microbes, such as, for instance, the infectious pneumonia of horned cattle. This was probably the first disease in which the protective effects of inoculation were tried according to Wilhelm’s method. This method consisted in making an incision under the animal’s tail with a scalpel dipped in the purulent mucus or blood taken from the lung of a beast which had died of pneumonia ; sometimes the serous discharge from the swelling under the tail of an inoculated animal was used for others. Fever and loss of appetite ensued, lasting from eight 146 MICROBES, FERMENTS, AND MOULDS. to twenty-five days, but the animal was afterwards safe from further attacks of the disease. Cattle plague, or contagious typhus, is likewise ascribed to the presence of a microbe with which we are as yet imperfectly acquainted. Experimental septicemia is entitled to special men- tion, since it has too often been confounded with anthrax, and has been unskilfully produced with the intention of vaccinating animals in accordance with Pasteur’s process. This occurs when too long an interval (twenty-four hours) elapses after the death of Vt Fig. 71.—Septic vibrio, bacillus of malignant cedema (Koch): u, taken from spleen of guinea-pig; b, from a mouse’s lung. an animal, before taking from it the blood intended for vaccine cultures. After this date the blood no longer contains Bacillus anthracis, which is succeeded by another microbe termed Vibrio septicus, differing widely from the anthrax microbe in form, habit, and character (Fig. 71). Bacillus anthracis is straight and immobile, while the septic vibrio is sinuous, curled, and mobile. Moreover, it is anaérobic, and does not survive contact with the air, but it thrives in a vacuum or in carbonic acid. Since Bacillus anthracis is, on OTHER DISEASES OF DOMESTIC ANIMALS. 147 the other hand, an aérobie, it is clear that the two microbes cannot exist simultaneously in the blood or in the same culture liquid. The inoculation with this fresh microbe is no less fatal; its action is even more rapid than that of Bacillus anthracis, but the lesions are not the same; the spleen remains normal, while the liver is discoloured. The septic vibrio is only found in minute quantities in the blood, so that it has escaped the notice of many observers. It is, however, found in immense numbers in the muscles, in the serous fluid of the intestines, and of other organs. It is very common in the intestines, and is probably the beginning of putrefaction. VI. RaABIEes. Rabies is a canine disease which is communicated by a bite, and the inoculation of man and other animals by the saliva. We are not yet precisely acquainted with the microbe which causes the disease, but Pasteur’s recent researches have thrown consider- able light on its life-history, which is still, however, too much involved in obscurity. It must first be observed that the hypothetical microbe of rabies, which no one has yet discovered, should not be confounded with the microbe of human saliva; this is found in the mouths of healthy persons, and will be briefly discussed in the following chapter, 148 MICROBES, FERMENTS, AND MOULDS. The following conclusions are the result of Pasteur’s researches into the virus of rabies. This virus is found in the saliva of animals and men affected by rabies, associated with various microbes. Inoculation with the saliva may produce death in three forms: by the salivary microbe, by the excessive development of pus, and finally by rabies. The brain, and especially the medulla oblongata, of men and animals which have died of rabies, is always virulent until putrefaction has set in. So also is the spinal cord. The virus is, therefore, essentially lucalized in the nervous system. Rabies is rapidly and certainly developed by tre- phining the bones of the cranium, and then inocu- lating the surface of the brain with the blood or saliva of a rabid animal. In this way there is a suppression of the long incubation which ensues from simple inoculation of the blood by a bite or intra-venous injection onany part of the body. It is probable that in this case the spinal cord is the first to be affected by the virus introduced into the blood; it then fastens on its tissues and multiplies in them. Asa general rule, a first attack which has not proved fatal is no protection against afresh attack. In 1881, however, a dog which had displayed the first symptoms of the disease of which the other animals associated with him had died, not only recovered, but failed to take rabies by trephining, when re-inoculated in 1882. Pasteur is now in possession of four dogs which are OTHER DISEASES OF DOMESTIC ANIMALS. 149 absolutely secured from infection, whatever be the mode of inoculation, and the intensity of the virus. All the other test dogs which were inoculated at the same time died of rabies. In 1884, Pasteur found the means of attenuating the virus. For this purpose he has inoculated a morsel of the brain of a mad dog into a rabbit’s brain, and has passed the virus proceeding from the rabbit “through the organism of a monkey, whence it becomes attenuated and a protective vaccine for dogs. This is the first step towards the extinction of this terrible disease. s VII. GLANDERS, This, again, is a disease easily transmitted from horses to man. Glanders, or farey, is caused by the presence of a bacterium, observed as early as 1868 by Christot and Kiener, and more recently studied at Berlin by Schiitz and Lofler. This microbe appears in the form of very fine rods (bacillus) in the lungs, liver, spleen, and nasal cavity. Babes and Havas found this bacillus in the human subject in 1881. Experimental cultures have been made simultaneously in France and Germany, and have given identical results. Bouchard, Capitan, and Charrin made their cultures in neutralized solutions of extract of meat, maintained at a temperature of 37°. By means of successive sowings, they have obtained the production of un- 150 MICROBES, FERMENTS, AND MOULDS. mixed microbes, presenting no trace of the original liquid, and this was done in vessels protected from air- germs. These cultures may be carried to the eighth generation. Asses and horses inoculated with liquid containing the microbes produced by this culture have died with the lesions characteristic of glanders (glanderous tubercles in the spleen, lungs, etc.). Cats and other animals which have been inoculated in the same way die with glanderous tubercles in the lymphatic glands and other organs. It follows from these experiments that the microbe which causes this disease is always reproduced in the different culture liquids with its characteristic form and dimensions ; that uni-ungulates can be inoculated with it, as well as man and other animals. In fact, this microbe is the essential cause of the disease. VIII. PEBRINE AND FLACHERIE, DISEASES AFFECTING SILKWORMS. We have already spoken of muscardine, a silk- worm’s disease produced by a microscopic fungus; two other diseases are caused by distinct microbes, of which we must shortly speak. Pebrine.—In the silkworm nurseries, in which this disease prevails, the silkworms which issue from the eggs, technically called seed, are slowly and irregularly developed, so as to vary greatly in size. Many die OTHER DISEASES OF DOMESTIC ANIMALS, 151 young, and those which survive the fourth moult shrink and shrivel away; they can hardly creep on to the heather to spin their cocoon, and produce scarcely any silk. On an examination of the worms which have died of this disease, De Quatrefages ascertained the presence of minute stains on the skin and in the interior of the body, which ‘he compared to a sprinkling of black pepper; hence the name pebrine. Under the microscope these stains assume the form of small mobile granules like bacteria, which Cornalia termed vibratile corpuscles, on account of their movements. Finally, Osimo and Vittadini ascertained the existence of these corpuscles in the eggs, and consequently showed that the epidemic might be averted by the sole use of healthy eggs, of which the soundness should be established by microscopic examination. It was at about this date, 1865, that Pasteur under- took the exhaustive study of pebrine; but Béchamp was the first to pronounce the disease parasitic, resembling muscardine in this respect, and caused by the attacks of a microbe—or microzyma, to adopt Béchamp’s name—of which the germ or spore is derived, from the air, at first attacking the silkworm from without, but multiplying in its interior, and developing with its growth, so that the infected moth is unable to lay its eggs without depositing the spores of the microbe at the same time, and thus exposing the young grub to attack as soon as it is born. Pasteur’s 152 MICROBES, FERMENTS, AND MOULDS. own researches soon induced him to adopt the same view. The pebrine microbe was long regarded as a true bacterium, successively described as Bacteriwm bom- bycis, Nosema bombycis (Fig. 72), and JQ? Panistophyton ovale. Balbiani’s recent °9°0 = researches tend to show that it should “7° oe be assigned to another group, much nearer to animals, and designated Fig. 12,— Nosema Sporozoaria. bombycis, pebrine ° : . ances Ge an Sporozoaria.—These protista, still regarded as plants by many naturalists, chiefly differ from bacteria by their mode of growth and reproduction, in which they resemble the para- sitic protozoaria, termed Psorospermia, Coccidies, and Gregarinide. In Sporozoaria, growth by fission, the rule in all bacteria, has not been observed; this distinction is fundamental. Sporozoaria multiply by free spore- formation in a mass of sarcode substance (protoplasm), resulting from the encysting of the primitive corpuscles (mother-cells). The formation of numerous spores may be observed within the mother-cells, having the appearance of pseudonavicelle or spores of gregari- nidee and psorospermia (parasites of vertebrate animals), Balbiani forms these organisms, which are found in many insects, into a small group, which he terms Microsporidia, The ripe spores are the vibratile corpuscles of OTHER DISEASES OF DOMESTIC ANIMALS. 153 Cornalia. They closely resemble the spores of some bacilli (B. amylobacter, for instance), and their germi- nation is likewise effected by perforation of the spore at one end, and issue of the protoplasm from the interior. This, however, does not issue in a rod-like form (Bacillus), but in that of a small protoplasmic mass, with amceboid movements, a characteristic not observed in any bacterium (Balbiaui). The other species of silkworms which have been recently introduced, notably the oak silkworm from China (Attacus Pernyi), are attacked by microsporidia analogous to those of pebrine. Pasteur has indicated the mode of averting the ravages of this disease. He has thus addressed the breeders: “If you wish to know whether a lot of cocoons will yield good seed, separate a portion of them and subject them to heat, which will accelerate the escape of the moth by four or five days, and examine them under the microscope to ascertain whether cor- puscles of pebrine are present. If they are, send all the cocoons to the silk factory. If they are not diseased, allow them to breed, and the seed will be good and will hatch out successfully. In a word, start with absolutely healthy seed, produced by absolutely pure parents, and. rear them under such conditions of cleanliness and isolation as may ensure immunity from infection.” When the disease is developed, fumigation with sulphurous acid is recommended, or preferably with 8 154 MICROBES, FERMENTS, AND MOULDS. creosote or carbolie acid, which do not affect the silk- worms (Béchamp), and which hinder the development of microsporidia. These fumigations likewise keep the litter from becoming corrupt, and in a properly conducted nursery the litter is kept dry. Flacherie—Wrongly confounded with pebrine, the disease flacherie is still more destructive to silkworms. The symptoms are remarkable. The rearing of silk- worms often goes on regularly up to the fourth moult, and success seems assured, when the silkworms suddenly cease to feed, avoid the leaves, become torpid, and perish, while still retaining an appearance of vitality, so that it is necessary to touch them in order to ascer- tain that they are dead. In this state they are termed morts-flats. A few days, sometimes even a few hours, suffice to transform the most flourishing nursery into a charnel-house. Pasteur examined these morts-flats, and found that the leaves contained in the stomach and intestine were full of bacteria, resembling those which are developed when the leaves are bruised in Es eas a glass of water and left to putrefy or & oo (Fig. 73). In a healthy specimen, a. of good digestion, these bacteria MF ae (aban Mackerig are never found. It is therefore microbe (x 990 Glam). evident that the disease is owing to bad digestion, and becomes rapidly fatal in animals which consume an enormous amount of food, and do nothing but eat from morning to night. The digestive OTHER DISEASES OF DOMESTIC ANIMALS. 155 ferments of unhealthy silkworms do not suffice to destroy the bacteria of the leaves, nor to neutralize their injurious effects. These bacteria are really the cause of the disease, for if even a minute quantity of the leaves taken from the intestine of diseased silkworms be given to healthy specimens, they sgon die of the same disease. It is, therefore, essentially contagious, and in order to prevent the diseased silkworms from contaminating the healthy by soiling the leaves on which the latter are about to feed, as much space should be assigned to them as possible. Good seed should also be selected, since it has been ascertained that some lots of seed are more liable to the disease than others. The affection does not indeed begin in the egg, as in pebrine, but the question of heredity comes in. It is clear that when a silkworm has been affected by flacherie without dying of it, its eggs will have little vitality, and the grubs which issue from them will be predisposed by their feeble constitu- tion to contract the disease. 156 MICROBES, FERMEN‘S, AND MOULDS, CHAPTER V. THE MICROBES OF HUMAN DISEASES. I. Microses oF Arr, EARTH, AND WATER. Ir is generally admitted that the large majority of epidemic and contagious diseases which affect men and animals are caused by the introduction of certain kinds of microbes into the organism. In reply to the question how these microbes are introduced into the body, and where they are before entering it, it is easy to show that these microbes exist in immense numbers —they or their spores—in the air we breathe, in the water we drink, in the ground on which we tread, and whence there rises, whenever it is dry, a fine dust charged with all sorts of germs, which penetrate together with the air into our mouths and lungs. For a long while we were almost completely ignorant of the conditions of existence of these microbes when they are in the soil or water. The recent researches of Zopf, a German botanist, tend to show that among the inferior alge termed Bacteria » THE MICROBES OF HUMAN DISEASES. 157 or Schizophyta, there is a very remarkable dimorphism of mode and habitat. In Beggiatoa of sulphurous waters, for instance, and in Cladothriz, which forms a whitish pellicle on the surface of putrefying liquids, Zopf has found, under certain conditions, all the forms designated as Micrococcus, Bacillus, Leptothrix, and Bacterium; that jis, microbes strictly so called, in- cluding those which are the producing agents of contagious diseases. Where these alge are found in water or on a damp soil, conditions of existence favourable to their develop- ment, there they live and multiply. But when the soil dries up, when a river returns to its bed after a flood, or a marsh disappears in consequence of the evaporation of its waters, all these alge give forth dormant spores, destined to ensure their propagation. We have described the formation of these spores by concentration of the protoplasm in the interior of each cell; in this form their volume is very small, and they are extremely light, so that as soon as they are desiccated, and then only, these spores are carried away by the slightest breeze and borne to great dis- tances. ‘hese are termed air-germs. When these moving germs encounter a favourable medium, at once moist and warm, such as the human mouth or lungs, they fasten there and are immediately developed, first in the form of Micrococcus, then of that of Bacterium, Bacillus, or Leptothria, according to the species to which the spore in question belongs. 158 MICROBES, FERMENTS, AND MOULDS. Schizophyta may therefore have two very different modes of existence, comparable to the hetereecia (change of habitat) and dimorphism of the fungi Ascomycetes and Basidiomycetes. Schizomycetes however, although, like fungi, they obtain their nourishment from organic substances which have been already elaborated, are not true parasites in the first stage of their existence, during which stage they live freely in the water, or on the damp soil. They become true parasites when they penetrate into the blood and tissues of man, in which they necessarily live at the expense of their host. Hence it may be seen why half-dried marshes, meadows from which a river has retreated in order to return to its bed, great excavations of the soil necessary in railway-cuttings, etc, become the source of a large number of epidemic or contagious diseases. In all these places the subsiding waters have left Schizophyta, or microbes in a dried state, and these are soon transformed into dormant spores, which are diffused through the air and enter the mouth and lungs of men living near the rivers and marshes, or who are working on the railway-cutting. The soil which has remained undisturbed for a long while is full of dormant spores, drawn into it by the rain to a greater or less depth; these may preserve their vitality for many years, waiting for the favourable medium which leads to their fresh development. An acquaintance with air-germs, with the microbes of earth and water, has therefore become indispensable THE MICROBES OF HUMAN DISEASES. 159 to the physician and to the professor of hygiene, who are anxious to decide on the precise cause of great epidemics in order, if possible, to foresee and avert them. This new branch of meteorology has been termed atmospheric micrography, since it necessarily involves the use of the microscope. The Microbes, of the Atmosphere.—In the observa- tory of Montsouris, Paris, there is now a special laboratory under the direction of Miquel, with the object of studying the living organisms of the air, of establishing statistics of their times and seasons, Figs. 74, 75.—Microbes and spores of atmospheric dust, mixed with amorphous particles, and collected by the aéroscope. and of drawing general conclusions as to the hygienic condition of the air, according as it is more or less charged with the microbes and spores which are factors of disease. This laboratory is provided with the apparatus necessary for such kinds of research. The first of these apparatus serves to collect the living organisms which are always mingled with a large amount of inert dust (Figs. 74, 75). The 160 MICROBES, FERMENTS, AND MOULDS. apparatus is founded on the principle of the aéroscope, invented by Pouchet for the examination of air-dust. It consists of a small cylinder in which a current of air is produced by means of an aspirator, on which running water acts, similar to those in use in all laboratories of physics and chemistry.