to Cryptogamic Botany" from Sphærotheca Castagnei, which is the hop mildew.* The vine disease, hop mildew, and rose mildew, are the most destructive species of this group, and the constant annoyance of cultivators.

When first describing an allied fungus found on old paper, and named Ascotricha chartarum, the Rev. M. J. Berkeley called attention to the presence of globose conidia attached to the threads which surround the conceptacles, and this occurred as long since as 1838. In a recent species of Chatomium found on old sacking, Chatomium griseum, Cooke, we have found tufts in all respects similar externally to the Chatomium, but no perithecium was formed, naked conidia being developed apparently at the base of the coloured threads. In Chatomium funicolum, Cooke, a black mould was also found which may possibly prove to be its conidia, but at present there is no direct evidence.

The brothers Tulasne have made us acquainted with a greater number of instances amongst the Sphæriacei in which multiple organs of reproduction prevail. Very often old and decaying individuals belonging to species of Boletus will be found filled, and their entire substance internally replaced, by the threads and multitudinous spores of a golden yellow parasite, to which the name of Sepedonium chrysospermum has been given. According to Tulasne, this is merely a condition of a sphæriaceous fungus belonging to his genus Hypomyces.§

The same observers also first demonstrated that Trichoderma viride, P., was but the conidia-bearing stage of Hypocrea rufa, P., another sphæriaceous fungus. The ascigerous stroma of the latter is indeed frequently associated in a very close manner with the cushions of the pretended Trichoderma, or in other cases the same stroma will give rise to a different apparatus of conidia, of which the principal elements are acicular filaments, which are short, upright, and almost simple, and which give rise to small

* See also Berkeley, in "Trans. Hort. Soc. London," vol. ix. p. 68.

+ Berkeley, in "Ann. Nat. Hist." (June, 1838), No. 116.

§ Tulasne, "On Certain Fungicolous Sphæriæ,". n "Ann. des Sci. Nat." 4me sér. xiii. (1860), p. 5.

oval conidia which are solitary on the tips of the threads. Therefore this Hypocrea will possess two different kinds of conidia, as is the case in many species of Hypomyces.

A most familiar instance of dualism will be found in Nectria cinnabarina, of which the conidia form is one of the most common of fungi, forming little reddish nodules on all kinds of dead twigs.*.

Almost any small currant twig which has been lying on the ground in a damp situation will afford an opportunity of studying this phenomenon. The whole surface of the twig will be covered from end to end with little bright pink prominences, bursting through the bark at regular distances, scarcely a quarter of an inch apart. Towards one end of the twig probably the prominences will be of a deeper, richer colour, like powdered cinnabar. The naked eye is sufficient to detect some difference between the two kinds of pustules, and where the two merge into each other specks of cinnabar will be visible on the pink projections. By removing the bark it will be seen that the pink bodies have a sort of paler stem, which spreads above into a somewhat globose head, covered with a delicate mealy bloom. At the base it penetrates to the inner bark, and from it the threads of mycelium branch in all directions, confined, however, to the bark, and not entering the woody tissues beneath. The head, placed under examination, will be found to consist of delicate parallel threads compacted to-. gether to form the stem and head. Some of these threads are simple, others are branched, bearing FIG. 104. Twig here and there upon them delicate little bodies, on the upper porwhich are readily detached, and which form the lower. mealy bloom which covers the surface. These are the conidia, little slender cylindrical bodies, rounded at the ends.

with Tubercularia

tion, Nectria on the

Passing to the other bodies, which are of a deeper colour, it

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

will soon be discovered that, instead of being simple rounded heads, each tubercle is composed of numerous smaller, nearly globose bodies, closely packed together, often compressed, all

B

FIG. 105.-Section of Tubercularia. c. Threads with conidia.*

united to a base closely resembling the base of the other tubercles. If for a moment we look at one of the tubercles near the spot where the crimson tubercles seem to merge into the pink, we shall not only find them particoloured, but that the red points are the identical globose little heads just observed in clusters. This will lead to the suspicion, which can afterwards be verified, that the red heads are really produced on the stem or stroma of the pink tubercles.

A section of one of the red tubercles will show us how much the internal structure differs. The little subglobose bodies which spring from a common stroma or stem are hollow shells or capsules, externally granular, internally filled with a gelatinous nucleus. They are, indeed, the perithecia of a sphæriaceous fungus of the genus Nectria, and the gelatinous nucleus contains the fructification. Still further examination will show that this fructification consists of cylindrical asci, each enclosing eight elliptical sporidia, closely packed together, and mixed with slender threads called paraphyses.

Here, then, we have undoubted evidence of Nectria cinnabarina, with its fruit, produced in asci growing from the stroma or stem, and in intimate relationship with what was formerly named Tubercularia vulgaris. A fungus with two forms of fruit,

* Figs. 104 to 106 by permission from the "Gardener's Chronicle."

one proper to the pink, or Tubercularia form, with naked slender conidia, the other proper to the mature fungus, enclosed in asci, and generated within the walls of a perithecium. Instances of this kind are now known to be far from uncommon, although

FIG. 106.-D. Nectria surrounding Tubercularia; E. tuft of Nectria cinnabarina; F. section of stroma; G. ascus aud paraphyses.

they cannot always, or often, be so clearly and distinctly traced as in the illustration which we have selected.

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.,* 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 bottlegreen, crowded in the centre of the Epochnium, then black granulated, sometimes depressed at the summit, with a minute The sporidia are strongly constricted in the centre, at first uniseptate, with two nuclei in each division.

pore.

green

Another Sphæria in which the association is undoubted is the

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

Sphæria aquila, Fr.,* 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.† The same authors have also figured the curious pentagonal conidia springing from flexuous threads accompanying Sphæria felina, Fckl.,‡ and also the threads resembling those of a Cladotrichum with the angular conidia of Sphæria cupulifera, B. and Br.§ 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. ||

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

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

↑ Berk. and Br. "Ann. Nat. Hist." (1865), No. 1096.

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

§ Ibid. No. 1333, pl. xxi. fig. 24.

|| Tulasne, "Selecta Fungorum Carpologia," ii. p. 269, pl. 29.