Chapter M: J. Berkeley (8)

It is not uncommon for the conidia of the _Sphæria_ to partake of the characteristics of a mould, and then the perithecia are developed amongst the conidial threads. A recently recorded instance of this relates to _Sphæria Epochnii_, B. and Br.,[L] the conidia form of which was long known before the _Sphæria_ related to it was discovered, under the name of _Epochnium fungorum_. The _Epochnium_ forms a thin stratum, which overruns various species of _Corticium_. The conidia are at first uniseptate. The perithecia of the _Sphæria_ are at first pale bottle-green, crowded in the centre of the _Epochnium_, then black green granulated, sometimes depressed at the summit, with a minute pore. The sporidia are strongly constricted in the centre, at first uniseptate, with two nuclei in each division.

Another _Sphæria_ in which the association is undoubted is the _Sphæria aquila_, Fr.,[M] which is almost always found nestling in a woolly brown subiculum, for the most part composed of barren brown jointed threads. These threads, however, produce, under favourable conditions, mostly before the perfection of the perithecia, minute subglobose conidia, and in this state constitute what formerly bore the name of _Sporotrichum fuscum_, Link., but now recognized as the conidia of _Sphæria aquila_.

In _Sphæria nidulans_, Schw., a North American species, we have more than once found the dark brown subiculum bearing large triseptate conidia, having all the characters of the genus _Helminthosporium_. In _Sphæria pilosa_, P., Messrs. Berkeley and Broome have observed oblong conidia, rather irregular in outline, terminating the hairs of the perithecium.[N] The same authors have also figured the curious pentagonal conidia springing from flexuous threads accompanying _Sphæria felina_, Fckl.,[O] and also the threads resembling those of a _Cladotrichum_ with the angular conidia of _Sphæria cupulifera_, B. and Br.[P] A most remarkable example is also given by the Brothers Tulasne in _Pleospora polytricha_, in which the conidia-bearing threads not only surround, but grow upon the perithecia, and are crowned by fascicles of septate conidia.[Q]

Instances of this kind have now become so numerous that only a few can be cited as examples of the rest. It is not at all improbable that the majority of what are now classed together as species under the genus of black moulds, _Helminthosporium_, will at some not very distant period be traced as the conidia of different species of ascomycetous fungi. The same fate may also await other allied genera, but until this association is established, they must keep the rank and position which has been assigned to them.

Another form of dualism, differing somewhat in character from the foregoing, finds illustration in the sphæriaceous genus _Melanconis_, of Tulasne, in which the free spores are still called conidia, though in most instances produced in a sort of spurious conceptaculum, or borne on short threads from a kind of cushion-shaped stroma. In the _Melanconis stilbostoma_,[R] there are three forms, one of slender minute bodies, oozing out in the form of yellow tendrils, which may be spermatia, formerly called _Nemaspora crocea_. Then there are the oval brown or olive brown conidia, which are at first covered, then oozing out in a black pasty mass, formerly _Melanconium bicolor_, and finally the sporidia in asci of _Sphæria stilbostoma_, Fries. In _Melanconis Berkeleii_, Tul., the conidia are quadrilocular, previously known as _Stilbospora macrosperma_, B. and Br. In a closely-allied species from North America, _Melanconis bicornis_, Cooke, the appendiculate sporidia are similar, and the conidia would also appear to partake of the character of _Stilbospora_. We may remark here that we have seen a brown mould, probably an undescribed species of _Dematiei_, growing in definite patches around the openings in birch bark caused by the crumpent ostiola of the perithecia of _Melanconis stilbostoma_, from the United States.

In _Melanconis lanciformis_,[S] Tul., there are, it would appear, four forms of fruit. One of these consists of conidia, characterized by Corda as _Coryneum disciforme_.[T] Stylospores, which are also figured by Corda under the name of _Coniothecium betulinum_; pycnidia,[U] first discovered by Berkeley and Broome, and named by them _Hendersonia polycystis_;[V] and the ascophorous fruits which constituted the _Sphæria lanciformis_ of Fries. Mr. Currey indicated _Hendersonia polycystis_, B. and Br., as a form of fruit of this species in a communication to the Royal Society in 1857.[W] He says this plant grows upon birch, and is in perfection in very moist weather, when it may be recognized by the large black soft gelatinous protuberances on the bark, formed by spores escaping and depositing themselves upon and about the apex of the perithecium. This I suspect to be an abnormal state of a well-known Sphæria (_S. lanciformis_), which grows upon birch, and upon birch only.

We might multiply, almost indefinitely, instances amongst the _Sphæriacei_, but have already given sufficient for illustration, and will therefore proceed briefly to notice some instances amongst the _Discomycetes_, which also bear their complete or perfect fruit in asci.

The beautiful purple stipitate cups of _Bulgaria sarcoides_, which may be seen flourishing in the autumn on old rotten wood, are often accompanied by club-shaped bodies of the same colour; or earlier in the season these clavate bodies may be found alone, and at one time bore the name of _Tremella sarcoides_. The upper part of these clubs disseminate a great abundance of straight and very slender spermatia. Earlier than this they are covered with globose conidia. The fully-matured _Bulgaria_ develops on its hymenium clavate delicate asci, each enclosing eight elongated hyaline sporidia, so that we have three forms of fruit belonging to the same fungus, viz. conidia and spermatia in the _Tremella_ stage, and sporidia contained in asci in the mature condition.[X] The same phenomena occur with _Bulgaria purpurea_, a larger species with different fruit, long confounded with _Bulgaria sarcoides_.

On the dead stems of nettles it is very common to meet with small orange tubercles, not much larger than a pin's head, which yield at this stage a profusion of slender linear bodies, produced on delicate branched threads, and at one time bore the name of _Dacrymyces Urticæ_, but which are now acknowledged to be only a condition of a little tremelloid _Peziza_ of the same size and colour, which might be mistaken for it, if not examined with the microscope, but in which there are distinct asci and sporidia. Both forms together are now regarded as the same fungus, under the name of _Peziza fusarioides_, B.

The other series of phenomena grouped together under the name of polymorphism relate to forms which are removed from each other, so that the mycelium is not identical, or, more usually, produced on different plants. The first instance of this kind to which we shall make reference is one of particular interest, as illustrative of the old popular creed, that berberry bushes near corn-fields produced mildewed corn. There is a village in Norfolk, not far from Great Yarmouth, called "Mildew Rollesby," because of its unenviable notoriety in days past for mildewed corn, produced, it was said, by the berberry bushes, which were cut down, and then mildew disappeared from the corn-fields, so that Rollesby no longer merited its _sobriquet_. It has already been shown that the corn-mildew (_Puccinia graminis_) is dimorphous, having a one-celled fruit (_Trichobasis_), as well as a two-celled fruit (_Puccinia_). The fungus which attacks the berberry is a species of cluster-cup (_Æcidium berberidis_), in which little cup-like peridia, containing bright orange pseudospores, are produced in tufts or clusters on the green leaves, together with their spermogonia.

De Bary's observations on this association of forms were published in 1865.[Y] In view of the popular belief, he determined to sow the spores of _Puccinia graminis_ on the leaves of the berberry. For this purpose he selected the septate resting spores from _Poa pratensis_ and _Triticum repens_. Having caused the spores to germinate in a moist atmosphere, he placed fragments of the leaves on which they had developed their secondary spores on young but full-grown berberry leaves, under the same atmospheric conditions. In from twenty-four to forty-eight hours a quantity of the germinating threads had bored through the walls and penetrated amongst the subjacent cells. This took place both on the upper and under surface of the leaves. Since, in former experiments, it appeared that the spores would penetrate only in those cases where the plant was adapted to develop the parasite, the connection between _P. graminis_ and _Æcid. berberidis_ seemed more than ever probable. In about ten days the spermogonia appeared. After a time the cut leaves began to decay, so that the fungus never got beyond the spermogonoid stage. Some three-year-old seedlings were then taken, and the germinating resting spores applied as before. The plants were kept under a bell-glass from twenty-four to forty-eight hours, and then exposed to the air like other plants. From the sixth to the tenth day, yellow spots appeared, with single spermogonia; from the ninth to the twelfth, spermogonia appeared in numbers on either surface; and, a few days later, on the under surface of the leaves, the cylindrical sporangia of the _Æcidium_ made their appearance, exactly as in the normally developed parasite, except that they were longer, from being protected from external agents. The younger the leaves, the more rapid was the development of the parasite, and sometimes, in the younger leaves, the luxuriance was far greater than in free nature. Similar plants, to the number of two hundred, were observed in the nursery, and though some of them had _Æcidium_ pustules, not one fresh pustule was produced; while two placed under similar circumstances, but without the application of any resting spores, remained all the summer free from _Æcidium_. It seems, then, indubitable so far that _Æcidium berberidis_ does spring from the spores of _Puccinia graminis_.

It has, however, to be remarked that De Bary was not equally successful in producing the _Puccinia_ from the spores of the _Æcidium_. In many cases the spores do not germinate when placed on glass, and they do not preserve their power of germinating very long. He reverts then to the evidence of experiments instituted by agriculturists. Bönninghausen remarked, in 1818, that wheat, rye, and barley which were sown in the neighbourhood of a berberry bush covered with _Æcidium_ contracted rust immediately after the maturation of the spores of the _Æcidia_. The rust was most abundant where the wind carried the spores. The following year the same observations were repeated; the spores of the _Æcidium_ were collected, and applied to some healthy plants of rye. After five or six days these plants were affected with rust, while the remainder of the crop was sound. In 1863 some winter rye was sown round a berberry bush, which in the following year was infested with _Æcidium_, which was mature in the middle of May, when the rye was completely covered with rust. Of the wild grasses near the bush, _Triticum repens_ was most affected. The distant plants of rye were free from rust.

The spores of the _Æcidium_ would not germinate on berberry leaves; the berberry _Æcidium_ could not therefore spring from the previous _Æcidium_. The uredospores of _Puccinia graminis_ on germinating penetrate into the parenchym of the grass on which they are sown; but on berberry leaves, if the tips of the threads enter for a short distance into the stomates their growth at once ceases, and the leaves remain free from parasites.

Montagne has, however, described a _Puccinia berberidis_ on leaves of _Berberis glauca_ from Chili, which grows in company with _Æcidium berberidis_. This at first sight seems to contradict the above conclusions; but the _Æcidium_ which from the same disc produces the puccinoid resting spores, appears to be different from the European species, inasmuch as the cells of the wall of the sporangium are twice as large, and the spores decidedly of greater diameter.[Z] The resting spores, moreover, differ not only from those of _Puccinia graminis_, but from those of all other European species.

From this account, then, it is extremely probable that the _Æcidium_ of the berberry enters into the cycle of existence of _Puccinia graminis_, and, if this be true, wherefore should not other species of _Puccinia_ be related in like manner to other _Æcidia_? This is the conclusion to which many have arrived, and, taking advantage of certain presumptions, have, we fear, rashly associated many such forms together without substantial evidence. On the leaves of the primrose we have commonly a species of _Æcidium_, _Puccinia_, and _Uromyces_ nearly at the same time; we may imagine that all these belong to one cycle, but it has not yet been proved. Again, _Uromyces cacaliæ_, Unger, _Uredo cacaliæ_, Unger, and _Æcidium cacaliæ_, Thumen, are considered by Heufler[a] to form one cycle. Numerous others are given by Fuckel,[b] and De Bary, in the same memoir from which we have already cited, notes _Uromyces appendiculatus_, Link., _U. phaseolorum_, Tul., and _Puccinia tragopogonis_, Ca., as possessing five kinds of reproductive organs. Towards the end of the year, shortly stipitate spores appear on their stroma, which do not fall off. These spores, which do not germinate till after a shorter or longer winter rest, may conveniently be called resting spores, or, as De Bary calls them, _teleutospores_, being the last which are produced. These at length germinate, become articulated, and produce ovate or kidney-shaped spores, which in their turn germinate, penetrating the cuticle of the mother plant, avoiding the stomates or apertures by which it breathes. After about two or three weeks, the mycelium, which has ramified among the tissues, produces an _Æcidium_, with its constant companion, spermogonia--distinct cysts, that is, from which a quantity of minute bodies ooze out, often in the form of a tendril, the function of which is imperfectly known at present, but which from analogy we regard as a form of fruit, though it is just possible that they may be rather of the nature of spermatozoids. The _Æcidia_ contain, within a cellular membranous sac, a fructifying disc, which produces necklaces of spores, which ultimately separate from each other in the form of a granular powder. The grains of which it is composed germinate in their turn, no longer avoiding the stomates as before, but penetrating through their aperture into the parenchym. The new resultant mycelium reproduces the _Uredo_, or fifth form of fructification, and the _Uredo_ spores fall off like those of the _Æcidium_, and in respect of germination, and mode of penetration, present precisely the same phenomena. The disc which has produced the _Uredo_ spores now gives rise to the resting spores, and so the cycle is complete.[c]

The late Professor Oersted, of Copenhagen, was of opinion that he had demonstrated the polymorphy of the Tremelloid Uredines, and satisfied himself that the one condition known as _Podisoma_ was but another stage of _Roestelia_.[d] Some freshly gathered specimens of _Gymnosporangium_ were damped with water, and during the night following the spores germinated profusely, so that the teleutospores formed an orange-coloured powder. A little of this powder was placed on the leaves of five small sorbs, which were damped and placed under bell-glasses. In five days yellow spots were seen on the leaves, and in two days more indications of spermogonia. The spermatia were discharged, and in two months from the first sowing, the peridia of _Roestelia_ appeared, and were developed. "This trial of spores," says Oersted, "has conduced to the result expected, and proves that the teleutospores of _Gymnosporangium_, when transported upon the sorb, give rise to a totally different fungus, the _Roestelia cornuta_, that is to say, that an alternate generation comes between these fungi. They appertain in consequence to a single species, and the _Gymnosporangium_ ceased to be an independent species, and must be considered as synonymous with the first generation of _Roestelia_. The spores have been transported upon young shoots of the juniper-tree, and have now commenced to produce some mycelium in the bark. There is no doubt that in next spring it will result in _Gymnosporangium_."

Subsequently the same learned professor instituted similar experiments upon other hosts, with the spores of _Podisoma_, and from thence he concluded that _Roestelia_ and _Podisoma_, in all their known species, were but forms the one of the other. Hitherto we are not aware that these results have been confirmed, or that the sowing of the spores of _Roestelia_ on juniper resulted in _Podisoma_. Such experiments should be received always with care, and not too hastily accepted in their apparent results as proven facts. Who shall say that _Roestelia_ would not have appeared on _Sorbus_ within two months without the sowing of _Podisoma_ spores?--because it is not by any means uncommon for that fungus to appear upon that plant. It is true many mycologists write and speak of _Roestelia_ and _Podisoma_ (or _Gymnosporangium_) as identical; but, as we think, without the evidence being so complete as to be beyond suspicion. It is, nevertheless, a curious fact that in Europe the number of species of _Roestelia_ and _Podisoma_ are equal, if one species be excluded, which is certainly not a good _Podisoma_, for the reception of which a new genus has been proposed.[e]

Amongst the ascigerous fungi will be found a curious but interesting genus formerly called _Cordyceps_, but for which Tulasne, in consequence of the discovery of secondary forms of fruit, has substituted that of _Torrubia_.[f] These curious fungi partake more or less of a clavate form, and are parasitic on insects. The pupæ of moths are sometimes seen bearing upon them the white branched mould, something like a _Clavaria_ in appearance, to which the name of _Isaria farinosa_ has been given. According to Tulasne, this is the conidia form of the bright scarlet, club-shaped body which is also found on dead pupæ, called _Torrubia militaris_. An American mould of the same genus, _Isaria sphingum_, found on mature moths,[g] is in like manner declared to be the conidia of _Torrubia sphingum_; whereas a similar mould, found on dead spiders, called _Isaria arachnophila_,[h] is probably of a similar nature. An allied kind of compact mould, which is parasitic on _Cocci_, on the bark of trees, recently found in England by Mr. C. E. Broome, and named _Microcera coccophila_,[i] is said by Tulasne to be a condition of _Sphærostilbe_, and it is intimated that other productions of a similar character bear like relations to other sphæriaceous fungi. For many species of _Torrubia_ no corresponding conidia are yet known.

Some instances might be noted, not without interest, in which the facts of dimorphism or polymorphism have not been satisfactorily proved, but final judgment is held in suspense until suspicion is replaced by conviction. Some years since, a quantity of dead box leaves were collected, on which flourished at the time a mould named _Penicillium roseum_. This mould has a roseate tint, and occurs in patches on the dead leaves lying upon the ground; the threads are erect and branched above, bearing chains of oblong, somewhat spindle-shaped spores, or, perhaps more accurately, conidia. When collected, these leaves were examined, and nothing was observed or noted upon them except this _Penicillium_. After some time, certainly between two and three years, during which period the box remained undisturbed, circumstances led to the examination again of one or two of the leaves, and afterwards of the greater number of them, when the patches of _Penicillium_ were found to be intermixed with another mould of a higher development, and far different character. This mould, or rather _Mucor_, consists of erect branching threads, many of the branches terminating in a delicate globose, glassy head, or sporangium, containing numerous very minute subglobose sporidia. This species was named _Mucor hyalinus_.[j] The habit is very much like that of the _Penicillium_, but without any roseate tint. It is almost certain that the _Mucor_ could not have been present when the _Penicillium_ was examined, and the leaves on which it had grown were enclosed in the tin box, but that the _Mucor_ afterwards appeared on the same leaves, sometimes from the same patches, and, as it would appear, from the same mycelium. The great difference in the two species lies in the fructification. In the _Penicillium_, the spores are naked, and in moniliform threads; whilst in _Mucor_ the spores are enclosed within globose membraneous heads or sporangia. Scarcely can we doubt that the _Mucor_ alluded to above, found thus intermixed, under peculiar circumstances, with _Penicillium roseum_, is no other than the higher and more complete form of that species, and that the _Penicillium_ is only its conidiiferous state. The presumption in this case is strong, and not so open to suspicion as it would be did not analogy render it so extremely probable that such is the case, apart from the fact of both forms springing from the same mass of mycelium. In such minute and delicate structures it is very difficult to manipulate the specimens so as to arrive at positive evidence. If a filament of mycelium could be isolated successfully, and a fertile thread, bearing the fruit of each form, could be traced from the same individual mycelium thread, the evidence would be conclusive. In default of such conclusive evidence, we are compelled to rest with assumption until further researches enable us to record the assumption as fact.[k]

Apropos of this very connection of _Penicillium_ with _Mucor_, a similar suspicion attaches to an instance noted by a wholly disinterested observer to this effect. "On a preparation preserved in a moist chamber, on the third day a white speck was seen on the surface, consisting of innumerable 'yeast' cells, with some filaments, branching in all directions. On the fourth day tufts of _Penicillium_, had developed two varieties--_P. glaucum_ and _P. viride_. This continued until the ninth day, when a few of the filaments springing up in the midst of the _Penicillium_ were tipped with a dewdrop-like dilatation, excessively delicate--a mere distended pellicle. In some cases they seemed to be derived from the same filament as others bearing the ordinary branching spores of _Penicillium_, but of this I could not be positive. This kind of fructification increased rapidly, and on the fourteenth day spores had undoubtedly developed within the pellicle, just as had been observed in a previous cultivation, precisely similar revolving movements being also manifested."[l] Although we have here another instance of _Mucor_ and _Penicillium_ growing in contact, the evidence is insufficient to warrant more than a suspicion of their identity, inasmuch as the equally minute spores of _Mucor_ and _Penicillium_ might have mingled, and each producing its kind, no relationship whatever have existed between them, except their development from the same matrix.

Another case of association--for the evidence does not proceed further--was recorded by us, in which a dark-coloured species of _Penicillium_ was closely associated with what we now believe to be a species of _Macrosporium_--but then designated a _Sporidesmium_--and a minute _Sphæria_ growing in succession on damp wall-paper. Association is all that the _facts_ warrant us in calling it.

We cannot forbear alluding to one of the species of _Sphæria_ to which Tulasne[m] attributes a variety of forms of fruit, and we do so here because we think that a circumstance so extraordinary should be confirmed before it is accepted as absolutely true. This refers to the common _Sphæria_ found on herbaceous plants, known as _Sphæria_ (_Pleospora_) _herbarum_. First of all the very common mould called _Cladosporium herbarum_ is constituted as conidia, and of this again _Macrosporium sarcinula_, Berk., is considered to be another condition. In the next place, _Cytispora orbicularis_, Berk., and _Phoma herbarum_, West., are regarded as pycnidia, enclosing stylospores. Then _Alternaria tenuis_, Pr.,[n] which is said to be parasitic on _Cladosporium herbarum_, is held to be only a form of that species, so that here we have (including the _perithecia_) no less than six forms or phases for the same fungus. As _Macrosporium Cheiranthi_, Pr., often is found in company with _Cladosporium herbarum_, that is also open to suspicion.

We have adduced in the foregoing pages a few instances which will serve to illustrate the polymorphism of fungi. Some of these it will be observed are accepted as beyond doubt, occurring as they do in intimate relationship with each other. Others are considered as scarcely so well established, but probable, although developed sometimes on different species of plants. Finally, some are regarded as hitherto not satisfactorily proved, or, it may be, only suspicious. In this latter group, however much probability may be in their favour, it can hardly be deemed philosophical to accept them on such slender evidence as in some cases alone is afforded. It would not have been difficult to have extended the latter group considerably by the addition of instances enumerated by various mycologists in their works without any explanation of the data upon which their conclusions have been founded. In fact, altogether this chapter must be accepted as illustrative and suggestive, but by no means as exhaustive.

[A] De Bary, in "Quarterly German Magazine" (1872), p. 197.

[B] The method pursued by Messrs. Berkeley and Hoffmann of
surrounding the drop of fluid, in which a definite number of
spores or yeast globules had been placed, with a pellicle of
air, into which the germinating threads might pass and
fructify, is perhaps the most satisfactory that has been
adopted, though it requires nice manipulation. If carefully
managed, the result is irrefragable, though doubts have been
cast, without any reason, on their observations.

[C] De Bary, "Uber die Brandpilze" (Berlin, 1853), pl. iv. figs. 3,
4, 5.

[D] A. de Bary, on Mildew and Fermentation, in "Quarterly German
Magazine," vol. ii. 1872.

[E] Berkeley, "Introd. Crypt. Bot." p. 78, fig. 20.

[F] See also Berkeley, in "Trans. Hort. Soc. London," vol. ix. p.
68.

[G] Berkeley, in "Ann. Nat. Hist." (June, 1838), No. 116.

[H] "Grevillea," vol. i. p. 176.

[I] Tulasne, "On Certain Fungicolous Sphæriæ," in "Ann. des Sci.
Nat." 4^me sér. xiii. (1860), p. 5.

[J] "A Currant Twig, and Something on it," in "Gardener's Chronicle,"
January 28, 1871.

[K] Figs. 104 to 106 by permission from the "Gardener's Chronicle."

[L] Berkeley and Broome, in "Annals of Natural History" (1866), No.
1177, pl. v. fig. 36; Cooke, "Handbook," ii. p. 866.

[M] Cooke, "Handbook," ii. p. 853, No. 2549; specimens in Cooke's
"Fungi Britannici Exsiccati," No. 270.

[N] Berk. and Br. "Ann. Nat. Hist." (1865), No. 1096.

[O] "Ann. Nat. Hist." (1871), No. 1332, pl. xx. fig. 23.

[P] Ibid. No. 1333, pl. xxi. fig. 24.

[Q] Tulasne, "Selecta Fungorum Carpologia," ii. p. 269, pl. 29.

[R] Cooke, "Handbook," ii. p. 878; Tulasne, "Carpologia," ii. p. 120,
plate 14.

[S] Tulasne, "Selecta Fung. Carp.," ii. plate 16.

[T] Corda, "Icones Fungorum," vol. iii. fig. 91.

[U] Corda, "Icones," vol. i. fig. 25.

[V] Berk. and Br. "Ann. Nat. Hist." No. 415.

[W] Currey, in "Philosoph. Trans. Roy. Soc." (1857), pl. 25.

[X] Tulasne, "On the Reproductive Apparatus of Fungi," in "Comptes
Rendus" (1852), p. 841; and Tulasne, "Selecta Fungorum
Carpologia," vol. iii.

[Y] "Monatsbericht der Koniglichen Preuss, Acad. der Wissenschaften
au Berlin," Jan. 1865; Summary, in "Journ. Roy. Hort. Soc.,
London," vol. i. n.s. p. 107.

[Z] We have before us an _Æcidium_ on leaves of _Berberis vulgaris_,
collected at Berne by Shuttleworth in 1833. It is named by him
_Æcidium graveolens_, and differs in the following particulars
from _Æcidium berberidis_. The peridia are scattered as in _Æ.
Epilobii_, and not collected in clusters. They are not so much
elongated. The cells are larger, and the orange spores nearly
twice the diameter. There is a decided, strong, but unpleasant
odour in the fresh plant; hence the name. The above figures
(figs. 107, 108) of the cells and spores of both species are
drawn by camera lucida to the same scale--380 diameters.

[a] Freiherrn von Hohenbühel-Heufler, in "Oesterr. Botan.
Zeitschrift," No. 3, 1870.

[b] Fuckel, "Symbolæ Mycologicæ" (1869), p. 49.

[c] Almost simultaneously with De Bary, the late Professor Oersted
instituted experiments, from which the same results ensued, as
to _Æcidium berberidis_ and _Puccinia graminis_. See "Journ.
Hort. Soc. Lond." new ser. i., p. 85.

[d] "Oversigt over det Kon. Danske Videns. Selskabs" (1866), p. 185,
t. 3, 4; (1867,) p. 208, t. 3, 4; "Résumé du Bulletin de la
Soc. Roy. Danoise des Sciences" (1866), p. 15; (1867), p. 38;
"Botanische Zeitung" (1867), p. 104; "Quekett Microscopical
Club Journal," vol. ii. p. 260.

[e] This is _Podisoma foliicola_, B. and Br., or, as proposed in
"Journ. Quekett Club," ii. p. 267, _Sarcostroma Berkeleyi_, C.

[f] Tulasne, "Selecta Fungorum Carpologia," iii. p. 6, pl. i. figs.
19-31.

[g] Cramer's "Papilio Exotic" (1782), fig. 267.

[h] Cooke, "Handbook," p. 548, No. 1639.

[i] Ibid. p. 556, No. 1666.

[j] Specimens were published under this name in Cooke's "Fungi
Britannici Exsiccati," No. 359.

[k] Cooke, "On Polymorphism in Fungi," in "Popular Science Review."

[l] Lewis's "Report on Microscopic Objects found in Cholera
Evacuations," Calcutta, 1870.

[m] Tulasne, "Selecta Fungorum Carpologia," ii. p. 261.

[n] Corda, "Prachtflora," plate vii.

X.

INFLUENCES AND EFFECTS.

It is no longer doubted that fungi exercise a large and very important influence in the economy of nature. It may be that in some directions these influences are exaggerated; but it is certain that on the whole their influence is far more important for evil and for good than that of any other of the Cryptogamia. In our endeavour to estimate the character and extent of these influences it will prove advantageous to examine them under three sections. 1. Their influence on man. 2. Their influence on lower animals. 3. Their influence on vegetation. Under these sections the chief facts may be grouped, and some approximate idea obtained of the very great importance of this family of inferior plants, and consequently the advisability of pursuing their study more thoroughly and nationally than has hitherto been done.

I. In estimating the influence of fungi upon man, we naturally enough seek in the first instance to know what baneful effects they are capable of producing on food. Although in the case of "poisonous fungi," popularly understood, fungi may be the passive agents, yet they cannot be ignored in an inquiry of this nature. Writing of the Uses of Fungi, we have already shown that a large number are available for food, and some of these real delicacies; so, on the other hand, it becomes imperative, even with stronger emphasis, to declare that many are poisonous, and some of them virulently so. It is not sufficient to say that they are perfectly harmless until voluntarily introduced into the human system, whilst it is well known that accidents are always possible, and probably would be if every baneful fungus had the word POISON inscribed in capitals on its pileus.

The inquiry is constantly being made as to what plain rules can be given for distinguishing poisonous from edible fungi, and we can answer only that there are none other than those which apply to flowering plants. How can aconite, henbane, oenanthe, stramonium, and such plants, be distinguished from parsley, sorrel, watercress, or spinach? Manifestly not by any general characters, but by specific differences. And so it is with the fungi. We must learn to discriminate _Agaricus muscarius_ from _Agaricus rubescens_, in the same manner as we would discriminate parsley from _Æthusa cynapium_. Indeed, fungi have an advantage in this respect, since one or two general cautions can be given, when none such are applicable for higher plants. For instance, it may be said truly that all fungi that exhibit a rapid change to blue when bruised or broken should be avoided; that all Agarics are open to suspicion which possess an acrid taste; that fungi found growing on wood should not be eaten unless the species is well known; that no species of edible fungus has a strong, unpleasant odour, and similar cautions, which, after all, are insufficient. The only safe guide lies in mastering, one by one, the specific distinctions, and increasing the number of one's own esculents gradually, by dint of knowledge and experience, even as a child learns to distinguish a filbert from an acorn, or with wider experience will thrust in his mouth a leaf of _Oxalis_ and reject that of the white clover.

One of the most deleterious of fungi that we possess is at the same time one of the most beautiful. This is the _Agaricus muscarius_, or Fly Agaric, which is sometimes used as a fly poison.[A] It has a bright crimson pileus studded with pale whitish (sometimes yellowish) warts, and a stem and gills of ivory whiteness. Many instances have been recorded of poisoning by this fungus, and amongst them some British soldiers abroad, and yet it cannot be doubted that this fungus is eaten in Russia. Two instances have come under our notice of persons with some botanical knowledge, and one a gardener, who had resided in Russia and eaten of this fungus. In one case the Fly Agaric was collected and shown to us, and in the other the figure was indicated, so that we might be under no doubt as to the species. Only one hypothesis can be advanced in explanation. It is known that a large number of fungi are eaten in Russia, and that they enter much into the domestic cookery of the peasantry, but it is also known that they pay considerable attention to the mode of cooking, and add a large amount of salt and vinegar, both of which, with long boiling, must be powerful agents in counteracting the poison (probably somewhat volatile) of such fungi as the Fly Agaric. In this place we may give a recipe published by a French author of a process for rendering poisonous fungi edible. It must be taken on his authority, and not our own, as we have never made the experiment, notwithstanding it seems somewhat feasible:--For each pound of mushrooms, cut into moderately small pieces, take a quart of water acidulated with two or three spoonfuls of vinegar, or two spoonfuls of bay salt. Leave the mushrooms to macerate in the liquid for two hours, then wash them with plenty of water; this done, put them in cold water and make them boil. After a quarter or half hour's boiling take them off and wash them, then drain, and prepare them either as a special dish, or use them for seasoning in the same manner as other species.[B]

This method is said to have been tried successfully with some of the most dangerous kinds. Of these may be mentioned the emetic mushroom, _Russula emetica_, with a bright red pileus and white gills, which has a clear, waxy, tempting appearance, but which is so virulent that a small portion is sufficient to produce disagreeable consequences. It would be safer to eschew all fungi with a red or crimson pileus than to run the risk of indulging in this. A white species, which, however, is not very common, with a bulbous base enclosed in a volva, called _Agaricus vernus_, should also be avoided. The pink spored species should also be regarded with suspicion. Of the _Boleti_ several turn blue when cut or broken, and these again require to be discarded. This is especially the case with _Boletus luridus_[C] and _Boletus Satanas_,[D] two species which have the under surface or orifice of the pores of a vermilion or blood-red colour.

Not only are species which are known to be poisonous to be avoided, but discretion should be used in eating recognized good species. Fungi undergo chemical changes so rapidly that even the cultivated mushroom may cause inconvenience if kept so long after being gathered as to undergo chemical change. It is not enough that they should be of a good kind, but also fresh. The employment of plenty of salt in their preparation is calculated very much to neutralize any deleterious property. Salt, pepper, and vinegar are much more freely employed abroad in preparing fungi than with us, and with manifest advantage.

It is undoubtedly true that fungi exert an important influence in skin diseases. This seems to be admitted on all hands by medical men,[E] however much they may differ on the question of the extent to which they are the cause or consequence of disease. Facts generally seem to bear out the opinion that a great number of skin diseases are aggravated, and even produced, by fungi. Robin[F] insists that a peculiar soil is necessary, and Dr. Fox says it is usually taught that tuberculous, scrofulous, and dirty people furnish the best nidus. It is scarcely necessary to enumerate all these diseases, with which medical men are familiar, but simply to indicate a few. There is favus or scall-head, called also "porrigo," which has its primary seat in the hair follicles. Plica polonica, which is endemic in Russia, is almost cosmopolitan. Then there is Tinea tonsurans, Alopecia, Sycosis, &c., and in India a more deeply-seated disease, the Madura Foot, has been traced to the ravages of a fungus described under the name of _Chionyphe Carteri_.[G] It is probable that the application of different names to the very often imperfect forms of fungi which are associated with different diseases is not scientifically tenable. Perhaps one or two common moulds, such as _Aspergillus_ or _Penicillium_, lie at the base of the majority, but this is of little importance here, and does not affect the general principle that some skin diseases are due to fungi.

Whilst admitting that there are such diseases, it must be understood that diseases have been attributed to fungi as a primary cause, when the evidence does not warrant such a conclusion. Diphtheria and thrush have been referred to the devastations of fungi, whereas diphtheria certainly may and does occur without any trace of fungi. Fevers may sometimes be accompanied by fungoid bodies in the evacuations, but it is very difficult to determine them. The whole question of epidemic diseases being caused by the presence of fungi seems based on most incomplete evidence. Dr. Salisbury was of opinion that camp measles was produced by _Puccinia graminis_, the pseudospores of which germinated in the damp straw, disseminated the resultant secondary bodies in the air, and caused the disease. This has never been verified. Measles, too, has been attributed freely, as well as scarlatina,[H] to fungal influences, and the endeavours to implicate fungi in being the cause of cholera have been pertinaciously persevered in with no conviction. The presence of certain cysts, said to be those of _Urocystis_, derived from rice, was announced by Dr. Hallier, but when it was shown that no such fungus was found on rice, this phase of the theory collapsed. Special and competent experts were sent from this country to examine the preparations and hear the explanations of Dr. Hallier on his theory of cholera contagion, but they were neither convinced nor satisfied.

As long ago as 1853, Dr. Lauder Lindsay examined and reported on cholera evacuations, and in 1856 he declared--"It will be evident that I can see no satisfactory groundwork for the fungus theory of cholera, which I am not a little surprised to find still possesses powerful advocates."[I] And of the examinations undertaken by him he writes:--"The mycelium and sporules of various species of fungi, constituting various forms of vegetable mould, were found in the scum of the vomit, as well as of the stools, but only at some stage of decomposition. They are found, however, under similar circumstances, in the vomit and stools of other diseases, and, indeed, in all decomposing animal fluids, and they are therefore far from peculiar to cholera."

Some writers have held that the atmosphere is often highly charged with fungi spores, others have denied the presence of organic bodies to any extent in the air. The experiments conducted in India by Dr. Cunningham[J] have been convincing enough on this point. This report states that spores and similar cells were of constant occurrence, and were generally present in considerable numbers. That the majority of the cells were living and ready to undergo development on meeting with suitable conditions was very manifest, as in those cases in which preparations were retained under observation for any length of time, germination rapidly took place in many of the cells; indeed, many spores already germinating were deposited on the slides. In few instances did any development take place beyond the formation of mycelium or masses of toruloid cells, but in one or two distinct sporules were developed on the filaments arising from some of the larger septate spores, and in a few others _Penicillium_ and _Aspergillus_ produced their characteristic heads of fructification.

With regard to the precise nature of the spores and other cells present in various instances little can be said, as, unless their development were to be carefully followed out through all its stages, it is impossible to refer them to their correct species or even genera. The greater number of them are apparently referable to the old orders of fungi--_Sphæronemei_, _Melanconei_, _Torulacei_, _Dematiei_, and _Mucedines_, while some probably belonged to the _Pucciniei_ and _Coæmacei_. Amongst those belonging to the _Torulacei_, the most interesting was a representative of the rare genus _Tetraploa_. Distinct green algoid cells occurred in some specimens. Then follow in the report details of observations made on the rise and fall of diseases, of which diarrhoea, dysentery, cholera, ague, and dengue were selected and compared with the increase or diminution of atmospheric cells. The conclusions arrived at are:--

"Spores and other vegetable cells are constantly present in atmospheric dust, and usually occur in considerable numbers; the majority of them are living, and capable of growth and development. The amount of them present in the air appears to be independent of conditions of velocity and direction of the wind, and their number is not diminished by moisture.

"No connection can be traced between the numbers of bacteria, spores, &c., present in the air, and the occurrence of diarrhoea, dysentery, cholera, ague, or dengue, nor between the presence or abundance of any special form or forms of cells, and the prevalence of any of these diseases.

"The amount of inorganic and amorphous particles and other débris suspended in the atmosphere is directly dependent on conditions of moisture and velocity of wind."

This report is accompanied by fourteen large and well-executed plates, each containing hundreds of figures of organic bodies collected from the air between February and September. It is valuable both for its evidence as to the number and character of the spores in the air, and also for the tables showing the relation between five forms of disease, and their fluctuations, as compared with the amount of spores floating in the atmosphere.

We are fain to believe that we have represented the influence of fungi on man as far as evidence seems to warrant. The presence of forms of mould in some of their incipient conditions in different diseased parts of the human body, externally and internally, may be admitted without the assumption that they are in any manner the cause of the diseased tissues, except in such cases as we have indicated. Hospital gangrene may be alluded to in this connection, and it is possible that it may be due to some fungus allied to the crimson spots (blood rain) which occur on decayed vegetation and meat in an incipient stage of decomposition. This fungus was at one time regarded as an algal, at another as animal; but it is much more probable that it is a low condition of some common mould. The readiness with which the spores of fungi floating in the atmosphere adhere to and establish themselves on all putrid or corrupt substances is manifest in the experience of all who have had to do with the dressing of wounds, and in this case it is a matter of the greatest importance that, as much as possible, atmospherical contact should be avoided.

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

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

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

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

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

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

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

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

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