Fungi: Their Nature and Uses

by M. C. Cooke

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, olive-green, brick-red, cinnamon-brown, reddish-brown, up to sepia-black 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 they are concealed, and we shall secure a crop.[C] 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.[D] 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.

Fig. 79.—(a) Basidia and spores of Exidia spiculosa; (b) Germinating spore.

The germination of the spore has been observed in some of the Tremellini. Tulasne described it in Tremella violacea.[E] 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 themselves, and directed perpendicularly to the axis of their figure. This appendage becomes filled with protoplasm at the expense of the spore, and its free and pointed extremity finally dilated into a sac, at first globose and empty. This afterwards admits into its cavity the plastic matter contained in its support, and, increasing, takes exactly the form of a new spore, without, however, quite equalling in size the primary or mother spore. The spore of the new formation long retains its pedicel, and the mother spore which produced it, but these latter organs are then entirely empty and extremely transparent. Sometimes two secondary spores are thus engendered from the same spore, and their pedicels may be implanted on the same or on different sides, so as to be parallel in the former case, and growing in opposite directions in the latter. The fate of these secondary spores was not determined.

Fig. 80.—Germinating spore and (a) corpuscles of Dacrymyces deliquescens.

In Dacrymyces deliquescens are found mingled amongst the spores immense numbers of small round or ovoid unilocular bodies, without appendages of any kind, which long puzzled mycologists. Tulasne ascertained that they are derived from the spores of this fungus when they have become free, and rest on the surface of the hymenium. Each of the cells of the spore emits exteriorly one or several of these corpuscles, supported on very short slender pedicels, which remain after the corpuscles are detached from them. This latter circumstance evidences that new corpuscles succeed the firstborn one on each pedicel as long as there remains any plastic matter within the spore. The latter, in fact, in consequence of this labour of production, becomes gradually emptied, and yet preserves the generative pedicels of the corpuscles, even when it no longer contains any solid or coloured matter. These pedicels are not all in the same plane, as may be ascertained by turning the spore on its longitudinal axis; but it often seems to be so when they are looked at in profile, on account of the very slight distance which then separates them one from another. It will also be remarked that they are in this case often implanted all on the same side of the reproductive body, and most often on its convex side. Their fecundity is exhausted with the plastic contents of the spore. The corpuscles, when placed in the most favourable conditions, have never given the least sign of vegetation; they have also remained for a long time in water without experiencing any appreciable alteration.

All the individuals of Dacrymyces deliquescens do not produce these corpuscles in the same abundance; those which bear the most are recognizable by the pale tint of the reproductive dust with which they are covered; in others, where this dust preserves its golden appearance, only a few corpuscles are found. The spores which produce corpuscles do not appear at all apt to germinate. On the other hand, multitudes of spores will germinate which had not produced any corpuscles. Tulasne remarks on this, that these observations would authorize us to think that all spores, though perfectly identical to our eyes, have not, without distinction, the same fate, nor doubtless the same nature; and, in the second place, that these two kinds of bodies, if they are not always isolated, yet are most frequently met with on distinct individuals. This author claims for the corpuscles in question that they are spermatia, and thinks that their origin is only so far unusual in that they proceed from veritable spores.

The whole of the Gasteromycetes have as yet to be challenged as to the mode and conditions of germination and development. It is probable that these will not materially differ from those which prevail in Hymenomycetes.