The existence of some sort of sexual reproduction in Fungi has long been suspected, although in earlier instances upon insufficient grounds; but of late years observations have multiplied and facts accumulated which leave no doubt of its existence. If the SaprolegniÆ are left out of the question as disputed Fungi, there still remain a number of well authenticated instances of the phenomena of copulation, and many other facts which indicate some sort of sexual relationship. The precise manner in which those minute bodies, so common amongst the SphÆronemei, which we prefer to call stylospores, perform their functions is still to a great extent a mystery; yet it is no longer doubted that certain species of AposphÆria, Phoma, Septoria, &c., are only conditions of some species of SphÆria, often developed and matured in close proximity to them on the same host. In Æcidium, Roestelia, &c., spermogonia are produced plentifully on or near the same spots on which the fructification appears, either simultaneously or at a later period.[A] The relation of Cytispora to Valsa was suspected by Fries very many years ago, and, as since demonstrated, with very good reason. All attempts, however, to establish anything like sexual reproduction in the higher forms of Hymenomycetes have at present been unsuccessful; and the same may be said of the Gasteromycetes; but in Ascomycetes and Physomycetes instances abound.

We know not whether any importance is to be attached to the views of M. A. S. Œrsted,[B] which have not since been confirmed, but which have been cited with some approval by Professor de Bary, as to a trace of sexual organs in Hymenomycetes. He is supposed to have seen in Agaricus variabilis, P., oocysts or elongated reniform cells, which spring up like rudimentary branches of the filaments of the mycelium, and enclose an abundant protoplasm, if not even a nucleus. At the base of these oocysts appear the presumed antheridia, that is to say, one or two slender filaments, which generally turn their extremities towards the oocysts, and which more rarely are applied to them. Then, without ulteriorily undergoing any appreciable modifications, the fertile cell or oocyst becomes enveloped in a network of filaments of mycelium which proceed from the one which bears it, and this tissue forms the rudiments of the cap. The reality of some kind of fecundation in this circumstance, and the mode of the phenomena, if there is one, are for the present equally uncertain. If M. Œrsted’s opinion is confirmed, naturally the whole of the cap will be the product of fecundation. Probably Karsten (Bonplandia, 1862, p. 62) saw something similar in Agaricus campestris, but his account is obscure.

In Phycomyces the organs of reproduction have been subjected to close examination by Van Tieghem,[C] and although he failed to discover chlamydospores in this, he describes them in other Mucors. In this species, besides the regular sexual development, by means of sporangia, there is a so-called sexual reproduction by means of zygospores, which takes place in this wise. The threads which conjugate to form the zygospores are slender and erect on the surface of the substratum. Two of these threads come into close contact through a considerable length, and clasp each other by alternate protuberances and depressions. Some of the protuberances are prolonged into slender tubes. At the same time the free extremities of the threads dilate, and arch over one towards the other until their tops touch like a vice, each limb of which rapidly increases in size. Each of these arcuate, clavate cells has now a portion of its extremity isolated by a partition, by means of which a new hemispherical cell is formed at the end of each thread at its point of junction with the opposed thread. These cells become afterwards cylindrical by pressure, the protoplasm is aggregated into a mass, the double membrane at the point of first contact is absorbed, and the two confluent masses of protoplasm form a zygospore invested with a tubercular coat and enveloped by the primary wall of the two conjugating cells. During this formation of the zygospore, the two arched cells whence the zygospore originated develop a series of dichotomous processes in close proximity to the walls which separate them from the zygospore. These processes appear at first on one of the arcuate cells in successive order. The first makes its appearance above upon the convex side; the succeeding ones to the right and left in descending order; the last is in the concavity beneath. It is only after the development of this that the first process appears on the opposite cell, which is followed by others in the same order. These dichotomous processes are nothing more than branches developed from the arcuate, or mother cells. During all these changes, while the zygospore enlarges, the wall of the arcuate cells becomes coloured brown. This colouring is more marked on the convex side, and it shows itself first in the cell on which the dichotomous branches are first produced, and which retains the darker tint longer than the other. The zone from whence the processes issue, and also the processes themselves, have their walls blackened deeply, while the walls of the conjugated cells, which continue to clothe the zygospore during the whole of its development, are bluish-black. By pressure, the thin brittle coat which envelopes the zygospore is ruptured, and the coat of the zygospore exposed, formed of a thick cartilaginous membrane, studded with large irregular warts.

The germination of the zygospores in this species has not as yet been observed, but it is probably the same or very similar to that observed in other species of Mucor. In these the rough tuberculate epispore splits on one side, and its internal coat elongates itself and protrudes as a tube filled with protoplasm and oil globules, terminating in an ordinary sporangium. Usually the amount of nutriment contained in the zygospore is exhausted by the formation of the terminal sporangium, according to Brefeld;[D] but Van Tieghem and Le Monnier remark that in their examinations they have often seen a partition formed at about a third of the length of the principal filament from the base, below which a strong branch is given off, and this is also terminated by a large sporangium.

De Bary has given a precise account of the formation of the zygospore in another of the Mucors, Rhizopus nigricans, in which he says that the filaments which conjugate are solid rampant tubes, which are branched without order and confusedly intermingled. Where two of these filaments meet each of them pushes towards the other an appendage which is at first cylindrical and of the same diameter. From the first these two processes are applied firmly one to the other by their extremities; they increase in size, become clavate, and constitute together a fusiform body placed across the two conjugated filaments. Between the two halves of this body there exists no constant difference of size; often they are both perfectly equal. In each there is collected an abundance of protoplasm, and when they have attained a certain development the largest extremity of each is isolated by a septum from the clavule, which thus becomes the support or suspender of the copulative cell. The two conjugated cells of the fusiform body are generally unequal; the one is a cylinder as long as it is broad, the other is disciform, and its length is only equal to half its breadth. The primitive membrane of the clavule forms between the copulative cells a solid partition of two membranes, but soon after the cells have become defined the medial partition becomes pierced in the centre, and then soon entirely disappears, so that the two twin cells are confounded in one single zygospore, which is due to the union of two more or less similar utricles. After its formation the zygospore still increases considerably in size, and acquires a diameter of more than one-fifth of a millimetre. Its form is generally spherical, and flattened on the faces which are united to the suspenders, or it resembles a slightly elongated cask. The membrane thickens considerably, and consists at the time of maturity of two superposed integuments; the exterior or epispore is solid, of a dark blackish-blue colour, smooth on the plane faces in contact with the suspenders, but covered everywhere else with thick warts, which are hollow beneath. The endospore is thick and composed of several layers, colourless, and covered with warts, which correspond and fit into those of the epispore. The contents of the zygospore are a coarsely granular protoplasm, in which float large oleaginous drops. While the zygospore is increasing in size, the suspender of the smaller copulative cell becomes a rounded and stipitate utricle, often divided at the base by a septum, and which attains almost to the size of the zygospore. The suspender of the larger copulative cell preserves its primitive form and becomes scarcely any larger. It is rare that there is not a considerable difference of size between the two conjugated cells and the suspenders.[E]

Similar conjugation with like results also takes place in Syzygites megalocarpus. In this species the germination of the zygospores has been observed. If, after a certain time of repose, these bodies are placed on a moist substratum, they emit a germ-like tube, which, without originating a proper mycelium, develops at the expense of the nutritive material stored in the zygospore into a carpophore or fruit bearer, which is many times dichotomously branched, bearing terminal sporangia characteristic of the species.

It has already been remarked by us that the Saprolegnei are claimed by some authors as AlgÆ, whilst we are more disposed to regard them as closely allied to the Mucors, and as they exhibit in themselves strong evidence in support of the existence of sexual reproduction, we cannot forbear giving a summary of what has been observed by De Bary and others in this very interesting and singular group of plants, to which M. Cornu has recently dedicated an exhaustive monograph.[F]

In Saprolegnia monoica, and others, the female organs consist of oogonia—that is to say, of cells which are at first globose and rich in plastic matter, which most generally terminate short branches of the mycelium, and which are rarely seen in an interstitial position. The constitutive membrane of the adult oogonia is reabsorbed in a great many points, and is there pierced with rounded holes. At the same time the plasma is divided into a larger or smaller number of distinct portions, which are rounded into little spheres, and separate from the walls of the conceptacle in order to group themselves at the centre, where they float in a watery fluid. These gonospheres are then smooth and bare, with no membrane on their surface of the nature of cellulose.

During the formation of the oogonia there arise from its pedicel or from neighbouring filaments slight cylindrical curved branches, sometimes turned round the support of the oogonia, and which all tend towards this organ. Their superior extremity is intimately applied to its wall, then ceases to be elongated, becomes slightly inflated, and is limited below by a partition; it is then an oblong cell, slightly curved, filled with protoplasm, and intimately applied to the oogonia—in fact, an antheridium or organ of the male sex. Each oogonium possesses one or several antheridia. Towards the time when the gonospheres are formed it may be observed that each antheridium sends to the interior of the oogonia one or several tubular processes, which have crossed its side wall, and which open at their extremity in order to discharge their contents. These, while they are flowing out, present some very agile corpuscles, and which, considering their resemblance to those in Vaucheria, to which the name of spermatozoids are applied, ought to be considered as the fecundating corpuscles. After the evacuation of the antheridia the gonospheres are found to be covered with cellulose; they then constitute so many oospores, with solid walls. De Bary considers that, bearing in mind analogous phenomena observed in Vaucheria, and the direct observations of Pringsheim,[G] the cellulose membrane on the surface of the gonospheres is only the consequence of a sexual fecundation.

In Achlya dioica the antheridium is cylindrical, the plasma which it encloses is divided into particles, which attain nearly the size of the zoospores of the same plant. These particles become globose cells, grouped in the centre of the antheridium. Afterwards the contents of these latter cells become divided into numerous bacillary spermatozoids, which first break the wall of their mother cell, and then issue from the antheridium. These rod-like corpuscles, which resemble the spermatozoids in Vaucheria, have their movements assisted by a long cilium. It is presumable that here, as in the AlgÆ, the spermatozoids introduce themselves into the cavity of the oogonium, and unite with the gonospheres.

Amongst obscure and doubtful bodies are those described by Pringsheim, which have their origin in thick filaments or tubes, similar to those which form the zoosporangia, and represent so many distinct little masses of plasma within an homogeneous parietal ganglion. The contour of these plastic masses is soon delineated in a more precise manner. We see in their interior some homogeneous granules, which are at first globose, then oval, and finally travel to the enlarged and ampullÆform extremity of the generating tube. There they become rounded or oval cells covered with cellulose, and emit from their surface one or several cylindrical processes, which elongate towards the wall of the conceptacle, and pierce it, without, however, ever projecting very far beyond it. At the same time the lacunose protoplasm of each cell becomes divided into a number of corpuscles, which escape by the open extremity of the cylindrical neck. They resemble in their organization and agility the spermatozoids of Achlya dioica. They soon become motionless in water, and do not germinate. During the development of these organs, the protoplasm of the utricle which contains them offers at first completely normal characteristics, and disappears entirely by degrees as they increase. De Bary and Pringsheim believe that these organs constitute the antheridia of the species of Saprolegnia to which they belong.

The oospores of the SaprolegniÆ, when arrived at maturity, possess a tolerably thick double integument, consisting of an epispore and an endospore. After a considerable time of repose they give rise to tubular or vesicular germs, which, without being much elongated, produce zoospores.[H]

De Bary has claimed for the oogonia in Cystopus and Peronospora a kind of fecundation which deserves mention here.[I] These same fruits, he says, which owe their origin to sexual organs, should bear the names of oogonia and antheridia, according to the terminology proposed by Pringsheim for analogous organs in the AlgÆ. The formation of the oogonia, or female organs, commences by the terminal or interstitial swelling of the tubes of the mycelium, which increase and take the form of large spherical or oboval cells, and which separate themselves by septa from the tube which carries them. Their membrane encloses granules of opaque protoplasm, mingled with numerous bulky granules of colourless fatty matter.

The branches of the mycelium which do not bear oogonia apply their obtuse extremities against the growing oogonia; this extremity swells, and, by a transverse partition, separates itself from the supporting tube. It is the antheridium, or male organ, which is formed by this process; it takes the form of an obliquely clavate or obovate cellule, which is always considerably smaller than the oogonium, and adheres to its walls by a plane or convex area. The slightly thickened membrane of the antheridia encloses protoplasm which is finely granular. It is seldom that more than one antheridium applies itself to an oogonium.

The two organs having together achieved their development, the large granules contained in the oogonium accumulate at its centre to group themselves under the form of an irregular globule deprived of a proper membrane, and surrounded by a bed of almost homogeneous protoplasm. This globule is the gonosphere, or reproductive sphere, which, through the means of fecundation, should become the reproductive body, vegetable egg, or oospore. The gonosphere having been formed, the antheridium shoots out from the centre of its face, close against the oogonium, a straight tube, which perforates the walls of the female cell, and traversing the protoplasm of its periphery, directs itself to the gonosphere. It ceases to elongate itself as soon as it touches it, and the gonosphere becomes clothed with a membrane of cellulose, and takes a regular spheroidal form.

Considering the great resemblance of these organs with the sexual organs of the SaprolegniÆ, which are closely allied to the AlgÆ, and of which the sexuality has been proved, De Bary adds, we have no doubt whatever that the phenomena just described represent an act of fecundation, and that the tube pushed out by the antheridium should be regarded as a fecundating tube. It is remarkable that amongst these fungi the tube projected by the antheridium effects fecundation only by contact. Its extremity never opens, and we never find antherozoids; on the contrary, the antheridium presents, up to the maturity of the oospore, the appearance which it presented at the moment of fecundation.

The primitive membrane of the oospore, at first very thin, soon acquires a more sensible thickness, and becomes surrounded by an external layer (epospore), which is formed at the expense of the protoplasm of the periphery. This disappears in proportion as the epispore attains maturity, and finally there only remains a quantity of granules, suspended in a transparent watery fluid. At the period of maturity, the epispore is a slightly thickened, resistant membrane, of a yellowish-brown colour, and finely punctate. The surface is almost always provided with brownish warts, which are large and obtuse, sometimes isolated, and sometimes confluent, forming irregular crests. These warts are composed of cellulose, which reagents colour of a deep blue, whilst the membrane which bears them preserves its primitive colour. One of the warts, larger than the rest, and recognizable by its cylindrical form, always forms a kind of thick sheath around the fecundating tube. The ripe endospore is a thick, smooth, colourless membrane, composed of cellulose containing a bed of finely granulated protoplasm, which surrounds a great central vacuole. This oospore, or resting spore, may remain dormant in this state within the tissues of the foster plant for some months. Its ultimate development by production of zoospores is similar to the production of zoospores from conidia, which it is unnecessary to repeat here. The oospore becomes an oosporangium, and from it at least a hundred germinating bodies are at length expelled.

Amongst the principal observers of certain phenomena of copulation in cells formed in the earliest stages of the Discomycetes are Professor de Bary,[J] Dr. Woronin,[K] and Messrs. Tulasne.[L] In the Ascobolus pulcherrimus of Crouan, Woronin ascertained that the cup derives its origin from a short and flexible tube, thicker than the other branches of the mycelium, and which is soon divided by transverse septa into a series of cells, the successive increase of which finally gives to the whole a torulose and unequal appearance. The body thus formed he calls a “vermiform body.” The same observer also seems to have convinced himself that there exists always in proximity to this body certain filaments, the short arched or inflected branches of which, like so many antheridia, rest their anterior extremities on the utriform cells. This contact seems to communicate to the vermiform body a special vital energy, which is immediately directed towards the production of a somewhat filamentous tissue, on which the hymenium is at a later period developed. This “vermiform body” of M. Woronin has since come to be recognized under the name of “scolecite.”

Tulasne observes that this “scolecite” or ringed body can be readily isolated in Ascobolus furfuraceus. When the young receptacles are still spherical and white, and have not attained a diameter exceeding the one-twentieth of a millimetre, it is sufficient to compress them slightly in order to rupture them at the summit and expel the “scolecite.” This occupies the centre of the little sphere, and is formed of from six to eight cells, curved in the shape of a comma.

In Peziza melanoloma, A. and S., the same observer succeeded still better in his searches after the scolecite, which he remarks is in this species most certainly a lateral branch of the filaments of the mycelium. This branch is isolated, simple, or forked at a short distance from its base, and in diameter generally exceeding that of the filament which bears it. This branch is soon arcuate or bent, and often elongated in describing a spiral, the irregular turns of which are lax or compressed. At the same time its interior, at first continuous, becomes divided by transverse septa into eight or ten or more cells. Sometimes this special branch terminates in a crozier shape, which is involved in the bent part of another crozier which terminates a neighbouring filament. In other cases the growing branch is connected, by its extremity, with that of a hooked branch. These contacts, however, did not appear to Tulasne to be so much normal as accidental. But of the importance of the ringed body, or “scolecite,” there was no room for doubt, as being the certain and habitual rudiment of the fertile cup. In fact, inferior cells are produced from the flexuous filaments which creep about its surface, cover and surround it on all sides, while joining themselves to each other. At first continuous, then septate, these cells by their union constitute a cellular tissue, which increases little by little until the scolecite is so closely enveloped that only its superior extremity can be seen. These cellular masses attain a considerable volume before the hymenium begins to show itself in a depression of their summit. So long as their smallness permits of their being seen in the field of the microscope, it can be determined that they adhere to a single filament of the mycelium by the base of the scolecite which remains naked.

Although Tulasne could not satisfy himself of the presence of any act of copulation in Ascobolus furfuraceus, or Peziza melanoloma, he was more successful with Peziza omphalodes. As early as 1860 he recognized the large globose, sessile, and grouped vesicles which originate the fertile tissue, but did not comprehend the part which these macrocysts were to perform. Each of these emits from its summit a cylindrical tube, generally flexuous, but always more or less bent in a crozier shape, sometimes attenuated at the extremity. Thus provided, these utricles resemble so many tun-shaped, narrow-necked retorts, filled with a granular thick roseate protoplasm. In the middle of these, and from the same filaments, are generated elongated clavate cells, with paler contents, more vacuoles, which Tulasne names paracysts. These, though produced after the macrocysts, finally exceed them in height, and seem to carry their summit so as to meet the crozier-like prolongations. It would be difficult to determine to which of these two orders of cells belongs the initiative of conjugation. Sometimes the advance seems to be on one side, and sometimes on the other. However this may be, the meeting of the extremity of the connecting tube with the summit of the neighbouring paracyst is a constant fact, observed over and over again a hundred times. There is no real junction between the dissimilar cells above described, except at the very limited point where they meet, and there a circular perforation may be discerned at the end, defined by a round swelling, which is either barely visible or sometimes very decided. Everywhere else the two organs may be contiguous, or more or less near together, but they are free from any adherence whatever. If the plastic matters contained in the conjugated cells influence one another reciprocally, no notable modification in their appearance results at first. The large appendiculate cell seems, however, to yield to its consort a portion of the plasma it contains. One thing only can be affirmed from these phenomena, that the conjugated cells, especially the larger, wither and empty themselves, while the upright compressed filaments, which will ultimately constitute the asci, increase and multiply.[M]

Certain phenomena concerned in the development of the Erysiphei belong also to this connection. The mycelium of Erysiphe cichoracearum, like that of other species, consists of branched filaments, crossed in all directions, which adhere as they climb to the epidermis of the plant on which the fungus lives as a parasite. The perithecia are engendered where two filaments cross each other. These swell slightly at this point, and each emits a process which imitates a nascent branch, and remains upright on the surface of the epidermis. The process originating from the inferior filament soon acquires an oval form and a diameter double that of the filament; then it becomes isolated from it by a septum, and constitutes a distinct cell, which De Bary[N] terms an oocyst. The appendage which proceeds from the inferior filament always adheres intimately to this cell, and elongates into a slender cylindrical tube, which terminates in an obtuse manner at the summit of the same cell. At its base it is also limited by a septum, and soon after another appears a little below its extremity at a point indicated beforehand by a constriction. This new septum defines a terminal short obtuse cell, the antheridium, which is thus borne on a narrow tube like a sort of pedicel. Immediately after the formation of the antheridia new productions show themselves, both around the oocyst and within it. Underneath this cell eight or ten tubes are seen to spring from the filament which bears it; these join themselves by the sides to each other and to the pedicel of the antheridium, while they apply their inner face to the oocyst, above which their extremities soon meet. Each of the tubes is then divided by transverse septa into two or three distinct cells, and in this manner the cellular walls of the perithecia come into existence.

During this time the oocyst enlarges and divides, without its being possible precisely to determine the way in which it happens, into a central cell and an outer layer, ordinarily simple, of smaller cells, contiguous to the general enveloping wall. The central cell becomes the single ascus, which is characteristic of the species, and the layer which surrounds it constitutes the inner wall of its perithecium. The only changes afterwards observed are the increase in size of the perithecium, the production of the root-like filaments which proceed from its outer wall, the brown tint which it assumes, and finally the formation of the sporidia in the ascus. The antheridium remains for a long time recognizable without undergoing any essential modification, but the dark colour of the perithecium soon hides it from the observer’s eye. De Bary thinks that he is authorized in assuming the probability that the conceptacles and organs of fructification of others of the Ascomycetes, including the Discomycetes and the Tuberacei, are the results of sexual generation.

Certain phenomena which have been observed amongst the Coniomycetes are cited as examples of sexual association. Amongst these may be named the conjugation of the slender spores of the first generation, produced on the germinating threads of Tilletia,[O] and similar acts of conjugation, as observed in some species of Ustilago. Whether this interpretation should be placed on those phenomena in the present condition of our knowledge is perhaps an open question.

Finally, the spermogonia must be regarded as in some occult manner, which as yet has baffled detection, influencing the perfection of sporidia[P] In Rhytisma, found on the leaves of maple and willow, black pitchy spots at first appear, which contain within them a golden pulp, in which very slender corpuscles are mixed with an abundant mucilage. These corpuscles are the spermatia, which in Rhytisma acerinum are linear and short, in Rhytisma salicinum globose. When the spermatia are expelled, the stroma thickens for the production of asci and sporidia, which are afterwards developed during the autumn and winter.

Several of the species of Hysterium also possess spermogonia, notably H. Fraxini, which may be distinguished from the ascigerous perithecia with which they are associated by their smaller size and flask-like shape. From these the spermatia are expelled long before the maturity of the spores. In Hypoderma virgultorum, H. commune, and H. scirpinum, the spermogonia are small depressed black capsules, which contain an abundance of minute spermatia. These were formerly regarded as distinct species, under the name of Leptostroma. In Stictis ocellata a great number of the tubercles do not pass into the perfect state until after they have produced either linear, very short spermatia, or stylospores, the latter being reproductive bodies of an oblong shape, equal in size to the perfect sporidia. Some of the tubercles never pass beyond this stage.

Again, there is a very common fungus which forms black discoid spots on dead holly leaves, called Ceuthospora phacidioides, figured by Greville in his “Scottish Cryptogamic Flora,” which expels a profusion of minute stylospores; but later in the season, instead of these, we find the asci and sporidia of Phacidium ilicis, so that the two are forms and conditions the one of the other.

In Tympanis conspersa the spermogonia are much more commonly met with than the complete fruit. There is a great external resemblance in them to the ascigerous cups, but there is no evidence that they are ever transformed into such. The perfect sporidia are also very minute and numerous, being contained in asci borne in cups, which usually surround the spermogonia.

In several species of Dermatea the stylospores and spermatia co-exist, but they are disseminated before the appearance of the ascigerous receptacles, yet they are produced upon a common stroma not unlike that of Tubercularia.

In its early stage the common and well-known Bulgaria inquinans, which when mature looks like a black Peziza, is a little tubercle, the whole mass of which is divided into ramified lobes, the extremities of which become, towards the surface of the tubercle, receptacles from whence escape waves of spermatia which are colourless, or stylospores mixed with them which are larger and nearly black.

Amongst the SphÆriacei numerous instances might be cited of minute stylosporous bodies in consort with, or preceding, the ascigerous receptacles. A very familiar example may be found at the base of old nettle stems in what has been named AposphÆria acuta, but which truly are only the stylospores of the SphÆria coniformis, the perithecia of which flourish in company or in close proximity to them. Most of these bodies are so minute, delicate, and hyaline that the difficulties in the way of tracing them in their relations to the bodies with which they are associated are very great. Nevertheless there is strong presumption in favour of regarding some of them as performing the functions which the name applied to them indicates.

Professor de Bary cautiously refrains from accepting spermatia other than as doubtful or at least uncertain sexual bodies.[Q] He says that the Messrs. Tulasne have supposed that the spermogonia represented the male sex, and that the spermatia were analogous to spermatozoids. Their opinion depends on two plausible reasons,—the spermatia, in fact, do not germinate, and the development of the spermogonia generally precedes the appearance of the sporophorous organs, a double circumstance which reminds us of what is known of the spermatozoids and antheridia of other vegetables. It remained to discover which were the female organs which underwent fecundation from the spermatia.

Many organs placed at first amongst spermatia have been recognized by M. Tulasne as being themselves susceptible of germination, and consequently ought to take their place among legitimate spores. Then it must be considered that very many spores can only germinate under certain conditions. It is, therefore, for the present a doubtful question whether there exist really any spermatia incapable of germination, or if the default of germination of these corpuscles does not rather depend on the experiments hitherto attempted not having included the conditions required by the phenomena. Moreover, as yet no trace has been discovered of the female organs which are specially fecundated by the spermatia.

Finally, there exist in the Ascomycetes certain organs of reproduction, diverse spore-bearing apparatus, pycnidia, and others, which, like the spermogonia, usually precede ascophorous fruits. The real nature of the spermogonia and spermatia should therefore be regarded as, at present, very uncertain; as regards, however, the spermatia which have never been seen to germinate, perhaps it is as well not to absolutely reject the first opinion formed concerning them, or perhaps they might be thought to perform the part of androspores, attributing to that expression the meaning which Pringsheim gives it in the ConferoÆ. The experiments performed with the spermatia which do not germinate, and with the spermogonia of the Uredines, do not, at any rate, appear to justify the reputed masculine or fecundative nature of these organs. The spermogonia constantly accompany or precede fruits of Æcidium, whence naturally follows the presumption that the first are in a sexual relation to the second. Still, when Tulasne cultivated Endophyllum sempervivum, he obtained on some perfectly isolated rosettes of Sempervivum some Æcidium richly provided with normal and fertile spores, without any trace of spermogonia or of spermatia.