posed, in which the sporidium (as in Perisporium vulgare) consists of four coloured ovate joints, which ultimately separate. Multiseptate fenestrate sporidia are not uncommon in Cucurbi

taria and Pleospora, as well as in Valsa fenestrata and some other species. In the North American Sphæria putaminum the sporidia are extraordinarily large.

The dissemination of the sporidia may, from identity of structure in the perithecium, be deemed to follow a like method in all. When mature, they are in a great measure expelled from the mouth of the perithecia, as is evident in species with large dark sporidia, such as exist in the genera Hypoxylon, Melanconis, and Massaria. In these genera the sporidia, on maturity, may be observed blackening the matrix round the mouths of the perithecia. As moisture has an evident effect in producing an expul

sion of sporidia by swelling the gelatinous nucleus, it may be assumed that this is one of the causes of expulsion, and therefore of aids to dissemination. When Sphæric are submitted to extra moisture, either by placing the twig which bears them on damp sand, or dipping one end in a vessel of water, the sporidia will exude and form a gelatinous bead at the orifice. There may be other methods, and possibly the successive production of new asci may also be one, and the increase in bulk by growth of the sporidia another; but of this the evidence is scanty.

Finally, OOGONIA may be mentioned as occurring in such genera as Peronospora amongst moulds, Cystopus amongst Uredines, and the Saprolegniacea amongst the Physomycetes. The zoospores being furnished with vibratile cilia, are for some time active, and need only water in which to disseminate themselves, and this is furnished by rain.

We have briefly indicated the characteristics of some of the more important types of spores to be found in fungi, and some of the modes by which it is known, or presumed, that their dissemination takes place. In this summary we have been compelled to rest content with suggestions, since an exhaustive essay would have occupied considerable space. The variability in the fruit of fungi, in so far as we have failed to demonstrate, will be found exhibited in the illustrated works devoted more especially to the minute species.*

66

* Corda, "Icones Fungorum," 6 vols. (1837-1842); Sturm, "Deutschlands Flora," Pilze (1841); Tulasne, "Selecta Fungorum Carpologia;" Bischoff, Kryptogamenkunde (1860); Corda, "Anleitung zum Studium der Mykologie" (1842); Fresenius, "Beiträge zur Mykologie" (1850); Nees von Esenbeck, "Das System der Pilze" (1816); Bonorden, "Handbuch der Allgemeinen Mykologie" (1851).

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VII.

GERMINATION AND GROWTH.

IN describing the structure of these organisms in a previous chapter, the modes of germination and growth from the spores have been purposely excluded and reserved for the present. It may be assumed that the reader, having followed us to this point, is prepared for our observations by some knowledge of the chief features of structure in the principal groups, and of the main distinctions in the classification, or at least sufficient to obviate any repetition here. In very many species it is by no means difficult to induce germination of the spores, whilst in others success is by no means certain.

M. de Seynes made the Hymenomycetes an especial object of study, but he can give us no information on the germination and growth of the spore. Hitherto almost nothing is positively known. As to the form of the spore, it is always at first spherical, which it retains for a long time, while attached to the basidia, and in some species, but rarely, this form is final, as in Ag. terreus, &c. The most usual form is either ovoid or regularly elliptic. All the Coprini have the spores oval, ovoid, more or less elongated or attenuated from the hilum, which is more translucent than the rest of the spore. This last form is rather general amongst the Leucospores, in Amanita, Lepiota, &c. At other times the spores are fusiform, with regularly attenuated extremities, as in Ag. ermineus, Fr., or with obtuse extremities, as

Seynes, J. de, "Essai d'une Flore Mycologique de la Montpellier," &c (1863), p. 30.

in Ag. rutilans, Sch. In Hygrophorus they are rather irregular, reniform, or compressed in the centre all round. Hoffmann* has given a figure taken from Ag. chlorophanus, and Seynes verified it upon Ag. ceraceus, Sow. (See figures on page 121.)

The exospore is sometimes roughened, with more or less projecting warts, as may be seen in Russula, which much resembles Lactarius in this as in some other particulars. The spores of the Dermini and the Hyporhodii often differ much from the sphærical form. In Ag. pluteus, Fr., and Ag. phaiocephalus, Bull, there is already a commencement of the polygonal form, but the angles are much rounded. It is in Ag. sericeus, Ag. rubellus, &c., that the polygonal form becomes most distinct. In Dermini the angles are more or less pronounced, and become rather acute in Ag. murinus, Sow., and Ag. ramosus, Bull. The passage from one to the other may be seen in the stellate form of the conidia of Nyctalis.

It is almost always the external membrane that is coloured, which is subject to as much variation as the form. The more fine and more delicate shades are of rose, yellow-dun or yellow, violet, ashy-grey, clear fawn colour, yellow-orange, olivegreen, brick-red, cinnamon-brown, reddish-brown, up to sepiablack and other combinations. It is only by the microscope and transparency that one can make sure of these tints; upon a sufficient quantity of agglomerated spores the colour may be distinguished by the naked eye. Colour, which has only a slight importance when considered in connection with other organs, acquires much in the spores, as a basis of classification.

With the growth of Agarics from the mycelium, or spawn, we are not deficient in information, but what are the conditions necessary to cause the spores themselves to germinate before our eyes and produce this mycelium is but too obscure. In the cultivated species we proceed on the assumption that the spores have passed a period of probation in the intestines of the horse, and by this process have acquired a germinating power, so that when expelled we have only to collect them, and the excrement in which

Hoffman, "Icones Analytica Fungorum."

they are concealed, and we shall secure a crop. * As to other species, we know that hitherto all attempts to solve the mystery of germination and cultivation has failed. There are several species which it would be most desirable to cultivate if the conditions could be discovered which are essential to germination.t In the same manner the Boleti and Hydnei-in fact, all other hymenomycetal fungi, with the exception of the Tremellini-still require to be interrogated by persevering experiment and close inquiry as to their mode of germination, but more especially as to the essential conditions under which alone a fruitful mycelium is produced.

The germination of the spore has been observed in some of the Tremellini. Tulasne described it in Tremella violacea. These spores are white, unilocular, and filled with a plastic matter of homogeneous appearance. From some portion of their surface an elongated germ filament is produced, into which the contents of the reproductive cell pass until quite exhausted. Other spores, perhaps more abundant, have a very different kind of vegetation. From their convex side, more rarely from the outer edge, these particular spores emit a conical process, generally shorter than FIG. 79.--(a) Basidia and spores themselves, and directed perpendicularly of Exidia spiculosa; (b) Germito the axis of their figure. This dage becomes filled with protoplasm at the expense of the

appen

nating spore.

The spores of Agarics which are devoured by flies, however, though returned in their dung in an apparently perfect state, are quite effete. It is, we believe, principally by the Syrphidae, which devour pollen, that fungus spores are consumed.

+ All attempts at Chiswick failed with some of the more esculent species, and Mr. Ingram at Belvoir, and the late Mr. Henderson at Milton, were unsuccessful with native and imported spawn.

Tulasne, "On the Organization of the Tremellini," "Ann. des. Sci. Nat." 3me sér. xix. (1853), p. 198.