Chapter IX: Fungi

The Fungi form the lowest class of plants: as examples of them, may be mentioned mushrooms, toadstools, puff-balls, the mould of paste, the blue mould of cheese, &c. The more minute Fungi are very common, forming beautiful microscopic objects, although they are rarely studied by the microscopic observer.

Fungi live usually upon rotting or decaying vegetable substances, as rotten wood, the dead leaves and stems of plants, &c.; but sometimes they are found upon living plants, and some of them exist upon decaying animal matters, and even in living animals.

Fungi exhibit no separation of root, stem, or leaves, as exists in the higher plants; nor do they contain chlorophyll, the presence of which is so generally associated with the idea of a plant. But they consist of aggregations of mostly elongate cells, forming branched and interlacing colourless fibres, buried like roots in the substance (matrix) upon which they grow, and from which they derive their nourishment; this portion of the Fungus is called the _mycélium_ (μὑκης, a fungus). The portion of the Fungus projecting beyond the surface of the matrix is the fructification; and this is the part usually called the fungus, the mycelium being overlooked by a casual observer. So that here we have a character distinguishing the Fungi from the Lichens, which derive their nourishment from the air, and not from the matrix. The absence of the green cells, or gonidia, forms another character by which the nearly allied members of this class of plants can be distinguished.

PLATE VII. [PAGE 96.]

FUNGI.

Fig.

1. _Agaricus micaceus_: _a_, gills.

2. _Agaricus campestris_: _a_, spores; _b_, basidia.

3. _Physarum album_, on a piece of stick.

4. _Physarum album_, spores.

5. _Uredo segetum_, spores.

6. _Uredo caries_, spores.

7. _Uredo candida_, on leaf of Shepherd’s Purse (_Capsella_): _s_, spores.

8. _Æcidium grossulariæ_, sorus.

9. _Æcidium grossulariæ_: _p_, spore-capsules (peridia); _s_, anther-capsules (spermogonia).

10. _Nemaspora crocea_: _a_, spores.

11. _Torula casei._

12. _Torula herbarum_, on a piece of stick.

13. _Torula herbarum_, spores.

14. _Phragmidium bulbosum_, on bramble-leaf.

15. _Phragmidium bulbosum_, stylo-spores and paraphyses.

16. _Puccinia graminis_, on a piece of straw.

17. _Puccinia graminis_, spores.

18. _Sporocybe alternata_, filament and spores.

19. _Botrytis parasitica_, on Shepherd’s Purse.

20. _Botrytis parasitica_, spores and filaments.

21. _Rhinotrichum_, species of.

22. _Rhinotrichum_, heads of spores.

23. _Rhinotrichum_, spores detached.

24. _Rhinotrichum_, spores.

25. _Penicillium glaucum._

26. _Penicillium glaucum_, head of spores.

27. _Coremium leucopus._

28. _Tubercularia vulgaris._

29. _Tubercularia vulgaris_, divided receptacle.

30. _Tubercularia vulgaris_, filaments.

31. _Tubercularia vulgaris_, spores.

32. _Sphæria fragiformis._

33. _Trichothecium roseum_, on a piece of stick.

34. _Trichothecium roseum._

35. _Trichothecium roseum_, filaments and spores.

W Bagg sculp

_London: John Van Voorst._]

The fructification of the Fungi occurs in two distinct forms, in one of which the seeds or spores are naked, and situated at the ends of slender cells or filaments, whilst in the other the spores are contained in usually flask-like cells, called asci, similar to those occurring in the Lichens. In a few Fungi, antheridial organs, called spermogonia, as in the case of the Lichens, have also been detected. The Fungi are divided into six Orders, from each of which a few species may be selected to illustrate their structure more in detail.

HYMENOMYCE´TES (ὑμἠν, membrane, μὑκης, fungus). This is the highest Order of Fungi, containing a large number of genera and species; as examples of which may be mentioned the common Mushroom, Toadstools, &c.

Their general structure may be illustrated by the examination of the common Mushroom (_Agar´icus campes´tris_); the species figured (Pl. VII. fig. 1), however, being _Agaricus micáceus_, which is common at the root of trees, the bottom of decaying posts, &c.

The vegetative part of the fungus consists of a cotton-like mycelium, which is composed of slender, colourless, interwoven filaments, popularly known as the spawn. The portion commonly called the mushroom corresponds to the fructification, and consists of certain parts visible to the naked eye. These are an expanded portion at the top, forming a hemispherical cap, receptacle, or _píleus_ (_pileus_, a cap), and a stalk, or _stípes_, upon which the cap is supported. On the under surface of the cap are a number of nearly parallel, radiating, dark-coloured plates or _gills_, somewhat resembling the gill-plates of a fish. The dark colour of the gills arises from the presence of the spores, which are coloured, although in some species they are white. The surface of the gills, upon which the spores are situated, is called the _hyménium_ (ὑμἠν, membrane). The spores (Pl. VII. fig. 2 _a_) are microscopic and very minute, and are situated at the ends of little stalks or points (Pl. VII. fig. 2 _b_), called _sterig´mata_ (στἡρυγμα, a prop), which are four in number, and consist of prolongations of the colourless cells of the hymenium; and these cells are the _basid´ia_ (βασἱδιον, a little base). The detection of the basidia requires great care, as they are very minute and transparent; the best way to observe them is to cut a very small portion from the uninjured edge of one of the gills with a fine pair of scissors, and to examine it in water. If the gills have been bruised, the spores are easily rubbed off, and their connexion with the basidia destroyed.

In the young state of the Mushroom, the fructification appears as little knobs upon the spawn or mycelium. Upon cutting these through perpendicularly, the cap and stalk are found to be enclosed in a skin or wrapper, called the _vol´va_ (_volva_, a wrapper), and the margin of the cap is continuous with the surface of the stalk, the connecting membrane forming the _veil_, or _vélum_ (_velum_, a veil). As the Fungus grows, the cap rises and bursts the volva, which withers and disappears; and the veil is torn through, the portion remaining in connexion with the stalk encircling it as a collar or ring (_an´nulus_).

_Merúlius lach´rymans_, the Dry-rot Fungus, which belongs to the same family (Agaricíni) as the Mushroom, deserves notice from its very destructive action upon decaying timber. The filaments of the mycelium may readily be detected in the rotting wood by examining a thin section in water. The receptacle forms a yellowish-orange or brownish flattened mass, some inches in breadth, with white downy margins; and the surface exhibits folds arranged so as to form large irregular pores, instead of gills as in the Mushroom.

In other families the cap and stalk appear fused together and undistinguishable; or the fructification assumes the form of the cap or the stalk only, and the hymenium does not form gills. Thus in the family Polyporei (the members of which are common on the trunks of trees and on rotten posts, and some of which are very large) the basidia are situated upon the inner surface of tubes immersed in the under part of the mass, their orifices forming minute pores, yet visible to the naked eye. In other families the basidia are placed upon the outer surface of a club-shaped or branched receptacle (Clavarini), or upon external prickle-like points (Hydnei), &c.

In the family Tremellini the receptacle forms a gelatinous mass, and the basidia are situated upon its surface, terminating the filaments of which it is composed. One species, _Dacrymy´ces stillátus_, is very common on fir posts in the winter and spring, forming little roundish, yellowish-orange, cushion-like masses.

GASTEROMYCE´TES (γαστἠρ, belly, hollow, μὑκης, fungus).--This order of Fungi, which contains the Puff-balls and many others not readily procured, must be very briefly noticed. The spores are contained in a capsule or perid´ium (πηρἱδιον, a little bag) which is often of large size, and are situated upon a hymenium forming folds, partitions (septa), or a lattice-work.

A small species, _Physárum album_ (Pl. VII. fig. 3), is often found growing upon rotten stems of plants and decaying sticks. The capsules are minute, grey, brittle, and black within, from the presence of the spores (fig. 4), which are lens-shaped, and arise from the ends of short filaments.

CONIOMYCE´TES (κὁνις, dust, μὑκης, fungus).--This Order contains some beautiful microscopic Fungi, several of which are very common. Many of them grow upon living plants, while others are found upon decaying stems, sticks, &c. The mycelium consists of inconspicuous, fine filaments, which run beneath the epidermis and bark of leaves and stems, or exist in the intercellular passages, the fruit bursting through the surface. The spores are short-stalked, forming _sty´lospores_ (στῦλος, stalk, σπὁρος, seed) or _conid´ia_ (κονἱδιον, little dust). But there is great confusion in the descriptions of the spores of the same Fungus by different botanical authors, some describing the fruit (in Pl. VII. fig. 15, for instance) as composed of rows of spores, while others regard it as forming a single septate (_septum_, a partition) or partitioned spore.

_Tor´ula herbárum_ (Pl. VII. fig. 12) is very common on the decaying stems of plants, especially those belonging to the Parsley order (Umbelliferæ), forming greenish-black streaks or patches. The spores (fig. 13) are grouped into chains or beaded (moniliform) rows, with very short stalks, and these are crowded to form the black patches visible to the naked eye. Under the microscope the spores appear of a brown colour.

_Torula cásei_ (Pl. VII. fig. 11) forms reddish or white patches upon decaying cheese. It consists of branched, interwoven, tufted filaments (_flocci_), with comparatively large spherical spores arranged in rows at their ends.

_Nemas´pora crócea_ (Pl. VII. fig. 10) is a very curious member of this Order, and is found upon decaying beech-sticks. It appears as an orange-coloured tendril-like gelatinous mass of spores, bursting through a little pore on the surface of the bark. The spores (fig. 10 _a_) are very minute, slender, and curved, and under a high power appear jointed.

_Æcid´ium grossuláriæ_ (Pl. VII. fig. 8) is found very commonly on the leaves of the gooseberry-bush. It forms to the naked eye oval or rounded spots (_sori_), of a red colour; and on close examination, the spots appear dotted with yellow points. Each point is the orifice of an open capsule (_peridium_), which has burst through the epidermis of the leaf (Pl. VII. fig. 9 _p_). The capsules are split or lacerated at the margins, and form little cups containing the spores. The spores are very minute, yellow, and are arranged in closely packed moniliform rows. The red colour depends upon the altered chlorophyll of the leaf. On the leaves containing the spore-capsules or peridia will be found smaller, brownish-yellow capsules (_spermogonia_) partly imbedded in their substance (Pl. VII. fig. 9 _s_). These contain minute filaments (_sterigmata_), terminated by short rows of rounded cells (_spermatia_), which are supposed to exert an antheridial function. The species of _Æcidium_ are very numerous, and many of them are extremely common--as those upon the nettle, the barberry, the dandelion, the wood-anemone, the violet, and buttercups. The groups of capsules form exquisite opake objects under a low power of the microscope.

_Phragmid´ium bulbósum_ (Pl. VII. fig. 14) is another very beautiful coniomycetous Fungus. It forms little reddish, afterwards sooty dots upon the under surface of the leaves of various species of Bramble (_Rúbus_). The oblong spores (fig. 15) are from 2-to 4-septate, and stalked, the stalks being swollen or bulbous at the base. The spores, which appear brown when magnified, are covered with little knobs (tuberculate) on the surface; and the uppermost little spore or sporidium is terminated by a minute point (apiculate). Among the spores are numerous barren filaments or paraphyses.

_Puccin´ia gram´inis_ (Pl. VII. fig. 16) is to be found everywhere upon damp rotting straw, and upon grasses. It forms sooty irregular streaks, consisting of densely crowded, one-partitioned (uniseptate) spores (fig. 17), which appear brown under the microscope. This Fungus is sometimes called “mildew.” There are numerous other species of _Puccinia_ which occur upon common plants.

_Urédo seg´etum_ is the “smut” of wheat, barley, and oats--a fungus too well known to the farmer. It forms sooty masses, bursting through the epidermis of the stalk and ears of the corn, and soiling the fingers when handled. The spores (Pl. VII. fig. 5) are exceedingly minute, and the stalks are so slender and loosely connected with them that they are not readily detected. Under the microscope the spores appear brown and faintly dotted, this appearance arising from a reticulated structure of the surface, similar to that of the poppy-seed on a very small scale.

_Urédo cáries_ is the “bunt” of corn. It grows within the grain, filling it with a sooty, fœtid mass. The spores (Pl. VII. fig. 6) are considerably larger than those of the last species, and their surface is distinctly reticulated. They are attached to the filaments of the mycelium, as in _Uredo segetum_.

The spores of both these species of _Uredo_ may be found in most kinds of flour and bread, especially in those of inferior quality.

_Urédo can´dida_ (Pl. VII. fig. 7) is another species, forming white dots upon the leaves of the common Shepherd’s Purse (_Capsel´la bur´sa pastor´is_)--which is easily recognized by the form and arrangement of the pods (fig. 19). The spores (_s_) are rather large and white.

Other species of _Uredo_ are very common upon numerous species of weeds or wild flowering plants; and they so closely resemble each other that, when one is known, the others are easily recognized. Usually each species occurs upon a distinct species of plant, as is the case with parasites generally. In many of them the spots (_sori_) exhibit a thin membrane covering the spores, which bursts down the middle, so as to bear some resemblance to a capsule. But there is no true capsule, the membrane consisting of the epidermis of the leaf or stalk of the plant, which is raised and torn by the expansion of the growing fungus; so that the peridium is spurious, as belonging to the matrix, and not to the fungus. It may be mentioned here that the so-called species of _Uredo_ are not truly distinct species, but are the forms of species of _Puccinia_, _Phragmidium_, &c.; so that the latter genera have two kinds of fruit, one of which is a _Uredo_, the other a _Puccinia_. But I must refer to the Dictionary for further details upon this point.

HYPHOMYCE´TES (ὑφἁω, to weave, μὑκης, fungus). In this, the 4th Order of Fungi, are contained many of the commonest moulds which are found growing upon decaying substances, and sometimes upon living plants. The mycelium creeps among the particles of the substance, or the elements of the tissues, upon which the Fungus lives, in the form of slender threads or filaments. The spores, which are either simple or partitioned (septate), and naked, occur either singly or in rows at the ends of fine interwoven cottony threads or _floc´ci_ (_floc´cus_, a flock of wool), which are generally very evident to the naked eye. The threads supporting the spores form the _ped´icels_ (_pedicel´lus_, a little foot). In technical descriptions, these filaments, which are usually composed of cells arranged end to end, are said to be _septate_ (Pl. VII. fig. 26), and not jointed, as in the case of the filaments of the _Confervæ_, which are constructed in a similar manner. When not septate, the filaments are said to be _continuous_.

STILBA´CEI.--To this family belongs _Tuberculária vulgaris_ (Pl. VII. fig. 28), which is found upon decaying sticks and branches of trees, especially the lime-tree. It forms little firm red knobs or tubercles, each of which is a receptacle. On making a section of a receptacle (Pl. VII. fig. 29), the interior is seen to be paler than the bright red surface, and a short broad stalk comes into view. The receptacle is composed of crowded cell-filaments, so short near the base as rather to resemble cellular tissue (fig. 30); but towards the surface the filaments become extremely slender and branched; and each branch is terminated by a minute oblong spore, or a short row of them (fig. 31).

If a stick with this Fungus upon it be kept for some time in a damp place, short whitish fibres, branched at the ends, and visible to the naked eye, will be seen sprouting from around the base of the receptacle (Pl. VIII. fig. 1). These, when examined under the microscope, appear composed of fine filaments (Pl. VIII. fig. 2), resembling those of _Tubercularia_, and having the minute spores at the ends. After a considerable time, the entire receptacle of the _Tubercularia_ becomes resolved into these fibres. In this state the Fungus assumes the characters of an _Isária_, a genus of a different family of Fungi (_Isariacei_), so that we have here an _Isaria_-form of _Tubercularia_.

Sometimes the tubercles of the _Tubercularia_ become darker, almost black, harder, and granular on the surface. On making a section of them in this state, the whole of the under portion of the surface is found to contain little roundish capsules, containing asci and spores, and it constitutes _Sphæ´ria fragifor´mis_ (Pl. VII. fig. 32). As the _Sphæria_ is the more complex and highly organized condition of this Fungus, the other two conditions must be regarded as forms, and not as species of separate genera.

DEMATIE´I.--In this family the filaments upon which the spores are placed are not compacted as in _Tubercularia_, but separate; and they are of a dark brown or black colour.

_Sporoc´ybe alternáta_ (Pl. VII. fig. 18) is occasionally found upon decaying vegetable substances, forming little black velvety spots or patches. The mycelial filaments are exceedingly minute, septate, tapering at the ends, and terminated by a little tuft of pear-shaped cells, from which the black simple spores arise singly.

PLATE VIII. [PAGE 104.]

FUNGI.

Fig.

1. _Isaria_-form of _Tubercularia_.

2. _Isaria_-form of _Tubercularia_, filaments.

3. _Aspergillus glaucus._

4. _Aspergillus glaucus_, filaments and heads of spores; _a_, separate spores.

5. _Aspergillus glaucus_, head of spores.

6. _Peziza omphalodes._

7. _Peziza stercorea._

8. _Peziza stercorea_, cup (receptacle).

9. _Peziza stercorea_, asci and paraphyses.

10. _Peziza stercorea_, divided receptacle.

11. _Peziza stercorea_, bristles.

12. _Dothidea typhina_, on leaf-stalk ofgrass.

13. _Dothidea typhina_, surface of patch (stroma).

14. _Dothidea typhina_, capsules (perithecia).

15. _Dothidea typhina_, ascus containing spores.

16. _Sphæria rubella_, on nettle-stem.

17. _Sphæria rubella_, asci.

18. _Sphæria rubella_, capsules (perithecia).

19. _Sphæria rubella_, ascus and spores.

20. _Sphæria bullata_, on piece of stick; 20 _a_, section of tubercle (receptacle).

21. _Sphæria bullata_, asci and spores.

22. _Sphæria complanata_, on piece of stick.

23. _Sphæria complanata_, tubercles (receptacles).

24. _Dothidea ulmi_, on elm-leaf.

25. _Dothidea ulmi_, asci.

26. _Dothidea ulmi_, section of receptacle.

27. _Dothidea ulmi_, spores.

28. _Chætomium elatum_; 28 _a_, spores; 28 _b_, filaments.

29. _Chætomium elatum_, on piece of stick.

30. _Hysterium fraxini_, on piece of stick.

31. _Hysterium fraxini_, receptacle.

32. _Hysterium fraxini_, ascus with spores.

33. _Erysiphe guttata_, on hazel-leaf.

34. _Erysiphe guttata_, capsule.

35. _Erysiphe guttata_, capsule (conceptacle) with fulcra.

36. _Mucor mucedo_: _a_, columella; _s_, spores.

37. _Acrostalagmus_: _a_, spores.

38. Gall on oak-leaf.

39. Gall on oak-leaf.

_W Bagg sculp_

_London: John Van Voorst._]

MUCED´INES.--Many of the Fungi belonging to this family are extremely common on decaying vegetable substances, and some are found upon living plants, to which they are very injurious. To the naked eye they usually appear as mouldy or cottony masses, either white, black, or coloured blue, yellow, &c. The spores are attached singly or in rows to branchlets arising from the ends of the filaments, so as to form little heads.

_Bot´rytis parasit´ica_ (Pl. VII. fig. 19) is common upon the flower-stalks of the Shepherd’s Purse, forming white mealy patches. The fruit-stalks are comparatively large and thin-walled, the branchlets being slender, mostly curved, and terminated each by a large, spherical, smooth, simple, white spore.

_Botrytis vulgáris_ is also common on various decaying plants. Its filaments are grey, and the branchlets lobe-like; the spores being minute, spherical, either white or greenish, and placed simply at the tips.

_Botrytis infes´tans_ is the potato-Fungus. It forms white spots upon the under side of the leaves of the potato-plant, and by some authors is considered to be the cause of the potato-disease. The filaments are branched at the ends, and terminated by single oval spores, which are apiculate at the free end, and contain minute little spores or sporidia.

_Oid´ium Tuck´eri_ is the well-known destructive grape-Fungus. It forms white cottony masses upon the vine and its grapes, the fruit-stalks being short and terminated by one or two end-to-end oblong spores. It appears to be the Coniomycetous form of another Fungus (_Erysiphe_).

_Trichothécium róseum_ (Pl. VII. fig. 33) is found upon rotting sticks; very frequently upon willow-baskets kept in a damp place. It forms little rounded, slightly raised, pinkish spots, less than the size of a pin’s head. The branched and septate foot-stalks (figs. 34, 35) are terminated each by a little group of obovate spores, divided by a transverse partition (uniseptate). Sometimes this little Fungus is quite white, at others greenish; when perfectly ripe, the spores become oblong.

_Penicil´lium glaúcum_ (Pl. VII. fig. 25) is the common Blue Mould found upon decaying substances, as cheese, &c., the interwoven mycelial filaments often forming large cakes or crusts upon the surface. The septate fruit-stalks (fig. 26) are fork-branched at the ends, the branchlets being terminated each by a row of very minute spherical smooth spores. On some decaying substances, as apples, gum, &c., the fruit-stalks are found aggregated into a thick stalk, the branchlets and spores forming a rounded head, so that the whole resembles a little blue mushroom (fig. 27). In this form the Fungus has been placed in a distinct genus, and called _Corémium leúcopus_. In other species the spores are pink and white.

This little Fungus is of special interest, on account of one form of it constituting the yeast-plant, or yeast as it is commonly called. This consists of rounded or oblong cells, which grow very rapidly in fermenting liquids by budding--the large quantity of sugar and gluten present favouring the vegetative or simple growing process, at the expense of the fructifying process. But this is only an instance of what we constantly find in flowering plants, the use of very rich soil rendering flowers double, which is really reducing their organs to the state of leaves. When the sugar has become exhausted, the cells of the yeast become longer and thinner, as if starved; they then form a more recognizable mycelium, which extends to the surface of the liquid, and produces finally the fruit-stalks and the _Penicillium_ fruit. _ Aspergil´lus glaúcus_ (Pl. VIII. fig. 3) is an extremely common mould upon cheese, jams, &c. It resembles the last in appearance to the naked eye, except that it has rather a green tinge, the heads of fruit being much more compact and rounded. The fruit-stalks (fig. 4) are large, bulbous or inflated at the ends (fig. 5), and from the inflations arise the crowded rows of spores. The spores are rounded, and rough (scabrous) on the surface. On removing most of the spores from the head of fruit, each row of spores is found to arise from a very short stalk.

Plate VII. fig. 21 represents a beautiful species of _Rhinot´richum_, which is found upon decaying and sickly plants, and upon rotting sticks, forming a minute grey mould. The fruit-stalks (fig. 22) are large, sparingly branched, septate or jointed, appearing brownish under the microscope. Their ends are branched, mostly biternate (fig. 23), _i. e._ each branch dividing into three branchlets, and these again into three still finer ones. The ends of the branchlets are inflated, and coated with little points, upon each of which a smooth white spore (fig. 24) is placed.

ASCOMYCÉTES (ἁσκὀς, a bottle, μὑκης, fungus). The Fungi belonging to this Order are found upon the stems and leaves of plants, and upon decaying substances, as dung, &c. They are usually evident to the naked eye, some even equalling the Hymenomycetous Fungi in size; and many of them are brilliantly coloured. They are in general distinguishable with facility from the Fungi of other Orders, by the arrangement of the spores in colourless sacs or asci (Pl. VIII. fig. 9), resembling those noticed in the case of the Lichens. These asci are usually enclosed in a capsule or _perithécium_. The mycelium is usually buried in the matrix, so as not to be conspicuous.

_Helvellácei._--To this family belongs the large genus _Pezíza_, some of the species of which are beautifully coloured, yet scarcely microscopic. Among these may be mentioned _Pezíza omphalódes_ (Pl. VIII. fig. 6), which forms little red masses upon damp ceilings. It does not possess the ordinary form of a _Peziza_, which is that of a cup fixed at the end of a stalk, like a mushroom with the cup turned inside out, the asci lining its interior.

_Peziza coccin´ea_ is not uncommon in woods. It is whitish outside, the interior of the cup being of a brilliant scarlet colour. It is from half an inch to an inch in height.

_Peziza stercor´ea_ (Pl. VIII. fig. 7) is often found upon dung. The surface of the cup of this Fungus is granular and covered with bristles (figs. 8 & 11). The cup is concave (fig. 10), and lined with the asci (fig. 9), among which are simple paraphyses.

The _Pezizæ_ are excellent Ascomycetous Fungi for exhibiting the asci, as they are more or less soft, and thus sections of them may be easily prepared, or they may readily be picked to pieces with the mounted needles.

TUBERACEI.--In this family is contained the Truffle (_Túber cibárium_). The asci are situated upon the inner surfaces of the winding canals traversing the substance of the fleshy fruit (_peridium_) of which the truffle consists.

PHACIDIA´CEI.--To this family belongs _Hystérium frax´ini_ (Pl. VIII. fig. 30), which is found upon ash-twigs. The drawn-out capsules or perithecia (fig. 31) are black and elliptical, with a longitudinal fissure or orifice, and contain the asci (fig. 32) with the spores.

SPHÆRIÁCEI.--_Dothid´ea typhína_ (Pl. VIII. fig. 12) is a common Fungus upon the stems of living grasses. It forms an orange-coloured patch or layer encircling the stem, and covered with little dots. On making a section (fig. 14), it appears composed of a row of oblong or obovate closely placed capsules (perithecia) immersed in and continuous with a finely fibrous receptacular mass (_stróma_). The asci (fig. 15) are very slender, arising in a tuft from the bottom of the capsules, and containing eight still more slender spores. Except under a very high power, the spores appear as interrupted lines running down the interior of the asci. The little dots visible to the naked eye are the slightly projecting mouths of the capsules, which are more distinctly seen in the magnified portion of the Fungus (fig. 13). In the young state, this Fungus is whitish.

This Fungus cannot be mistaken for a _Uredo_, two species of which occur upon grasses--_Uredo lineáris_ forming yellowish-brown spots, and _Uredo rubígo_ yellow spots.

_Dothidea ul´mi_ (Pl. VIII. fig. 24) forms black, slightly raised, and somewhat star-shaped spots upon the upper surface of the leaves of the elm. In a section (fig. 26) the cavities are seen, containing the very delicate asci (fig. 25). The spores (fig. 27) are oval, with a minute septum at one end.

_Sphæ´ria rubel´la_ (Pl. VIII. fig. 16) is extremely common on the dead stems of the nettle, &c. In this Fungus the black bottle-like perithecia (fig. 18), containing the asci and paraphyses (fig. 17), are at first situated beneath the epidermis, through which they at length burst. The spores (fig. 19 _a_) are spindle-shaped, and from four-to seven-septate. When ripe, they escape by a hole or pore in the neck.

_Sphæ´ria complanáta_ (Pl. VIII. fig. 22) is another common species, found in hedges, on dead sticks of the softer (herbaceous) plants, as the parsley-order (Umbelliferæ). Here the minute capsules, which are scattered over the stems, are at first rounded, then flattened on the top (depressed), the neck being very minute (fig. 23). The spores in this species are exceedingly minute, oblong, and not contained in asci.

_Sphæ´ria bulláta_ also belongs to this family. It occurs upon decaying birch-sticks, presenting to the naked eye the appearance represented in Pl. VIII. fig. 20. The black, raised tubercles (receptacles) in their growth burst through the bark, splitting the epidermis. They consist of a white stroma (fig. 20 _a_), in which the bottle-shaped capsules (perithecia) are immersed, the necks projecting slightly above the surface as little points (papillæ). The tufted spore-sacs or asci (fig. 21), with the thread-like paraphyses, are contained within the capsules; and within the asci are the densely packed, very numerous and minute curved spores.

Another species, _Sphæria discifor´mis_, is also common on birch-sticks. It differs from the last in the tubercles being perfectly flat; the spores are also longer, straight, and spindle-shaped (fusiform).

PERISPORÁCEI.--_Erys´iphe guttáta_ (Pl. VIII. fig. 33) is a member of this family. It appears on the under side of the leaves of the common hazel as a pale spot; and on closely examining it with the naked eye, little black dots are seen scattered on the surface. These are the capsules (conceptacles), which are seated upon straight white filaments. The filaments (_fulcra_) are six or seven in number, and are placed under the capsule, like the legs of a stool (fig. 34); they are rigid, and swollen or inflated at the base (fig. 35). The asci are broad and short, and contain only two spores.

_Erysiphe maculáris_ is the very destructive hop-mildew; and other species are common on various plants.

_Chætómium elátum_ (Pl. VIII. fig. 29) resembles little tufts of brown hairs, occurring upon decaying herbaceous stems. The capsule (fig. 28) is crustaceous, and covered with interlaced, rough, branched hairs (fig. 28 _b_). The spores (fig. 28 _a_) are oval, with a little point at one end (apiculate).

PHYSOMYCÉTES (φῦσα, bladder, μὑκης, fungus).--The Fungi belonging to this order include some of the commonest moulds growing upon decaying vegetable substances; while others are found upon leaves, &c. The flocci are generally very evident; and the spores are contained in little naked, bladder-like capsules (_peridíola_) at the ends of free filaments.

MUCORINI.--In this family we have the common mould of paste, _Múcor mucédo_ (Pl. VIII. fig. 36). It is easily recognized by the little spherical capsules terminating the long and tufted fruit-stalks (pedicels), which are perceptible to the naked eye. Each capsule consists of a simple enlarged cell, the cavity of which is separated from that of the stalk by a septum. They are white at first, subsequently becoming brown and black. The minute crowded spores (fig. 36 _s_) are at first oblong, afterwards spherical. In the centre of the capsule is a club-shaped body, or _columel´la_ (fig. 36 _a_), formed by the elevation and inflation of the septum.

A beautiful little Fungus of this family, apparently referable to the genus _Acrostalag´mus_ (Pl. VIII. fig. 37), is sometimes found upon soft decaying stems. The main filaments are soft, smooth, and not septate. The pedicels are very brittle, whorled, dichotomously branched, scabrous, and terminated each by a little scabrous spherical vesicle (fig. 37 _a_), containing two or three oblong spores.

ANTENNARIÉI.--In this family is _Racódium_ (or _Antennária_) _celláre_, the Wine-cellar Fungus, forming the well-known cobweb-like masses hanging from the walls, &c. The little black capsules are seated upon slender septate filaments, and contain numerous round spores.

In examining leaves with the view of procuring Fungi, the reader will most likely meet with the two kinds of bodies represented in Plate VIII. figs. 38 & 39. These are not Fungi, but galls. They arise from an abnormal growth of the leaf-structures, produced by the deposition of the eggs of insects (_Cynipidæ_). The well-known oak-apple, and the red hairy-looking body found upon hedge-roses, are both galls produced in the same way.

_Examination and Preservation._--The examination of the Fungi scarcely requires any special remarks. They should be viewed first as opake objects under a low power; and then sections should be made, or the textures separated with the mounted needles.

There is some difficulty in moistening the smaller filamentous Fungi with water, which is requisite in the determination of the arrangement of the spores upon the branches. Hence the best plan is to lay the Fungus upon a slide, apply a cover, then to add a drop of spirit of wine and afterwards a little water to the edge of the cover. When thus wetted, the spores may be more or less removed with a wet hair-pencil, when the ends of the branches will become perfectly distinct. In examination of the dried smaller Fungi as the _Sphæriæ_, the capsules should be macerated for a time in water.

The softer Fungi are very difficult of preservation in the entire state; but the sections or minute structures may be mounted in chloride of calcium or glycerine.

The harder and drier Fungi may be preserved by drying and gentle pressure between coarse absorbent paper. They may then be glued to pieces of paper and labelled, in the same manner as the flowering plants. Specimens of the capsules, as of the _Sphæriæ_, &c., may also be mounted in the dry state, the asci being preserved in the chloride of calcium or glycerine, in which liquids most of the smaller Fungi will keep extremely well.

PLATE IX. [PAGE 113.]

ANIMAL TISSUES, &c.

Fig.

1. Blood-corpuscles, Human.

2. Blood-corpuscles of Bird (Fowl).

3. Blood-corpuscles of Reptile (Frog).

4. Blood-corpuscles of Fish (Stickleback).

5. Hair of Bat.

6. Hair of Mouse.

7. Hair of Mouse.

8. Hair, human.

9. Hair, human.

10. Wool, fibre of.

11. Flax, fibres of.

12. Cotton, fibres of.

13. Silk, fibres of.

14. Feather, portion of: _a_, barbs; _b_, _c_, pinnæ.

15. Bone, section of: _a_, lacunæ.

16. Cartilage, section of.

17. Feather, downy.

18. Feather, downy: pinna.

19. Shell, pearly or nacreous portion of.

20. Muscle: _a_, cellular tissue; _b_, fibrillæ; _c_, bundle of fibrillæ.

21. Tongue of Whelk: _a_, natural size.

22. Scale of Dace.

23. Scale of Perch.

24. Scale of Cod.

25. Spermatozoa of Chub.

26. _Flustra foliacea_: _a_, cells of; _b_, animal, with the tentacles expanded.

27. _Flustra foliacea._

28. Shell of Oyster, brown portion of.

29. Shell of Oyster, prisms of.

30. _Cyclops quadricornis._

31. _Daphnia pulex_, female.

32. _Daphnia pulex_, head of male.

33. _Canthocamptus minutus_, an Entomostracan.

34. _Cypris tristriata._

35. _Cypris tristriata_, eggs of; 35 _a_, _b_, _c_, the same hatching.

36. _Acarus domesticus_ (Cheese-mite), female.

36*. Cilia of gills of Oyster.

37. _Trombidium fuliginosum_: _a_, pulp; _b_, mandible; _c_, foot; _d_, natural size; _e_, hair; _f_, hair of _T. holosericeum_.

38. _Acarus domesticus_, male.

39. _Membranipora pilosa._

W Bagg sculp

_London: John Van Voorst._]