The Sphæriacei, another order of Ascomycetes, are enormously numerous. There are 1,000 well known species of this order, and probably twice as many undetermined; for there is scarcely a twig or dry branch in the forests, hedges, or gardens on which they may not be found. The rose tree, the oak, and other plants harbour more than one species at a time. The genus Cordyceps and many so-called species of Sphæria are only the ultimate development of fungi of other families. The Cordyceps purpurea, discovered by M. Tulasne on the ergot of wheat, has a short, upright, slender stem, with a minute pale purple globose fruit-bearing head. In this ergotized state the white substance of the grain is converted into a firm mass without any appearance of meal, and having very powerful properties. When sown, it is found to produce the Cordyceps. Mr. Currey found the same plant on the ergot of the common reed, and there are several other species of Cordyceps, all of which are only the second form of ergot. To these may be added the Cordyceps militaris of Ehrenberg, already shown (p. 283) to be the ultimate development of the Isaria, which attacks the caterpillars of the bramble moth; and the Cordyceps Robertsii, which grows like a bunch of rushes from the head of the Hepialus virescens of New Zealand; whilst a kind of wasp in the West Indies, which continues to fly about after it is attacked, is at last killed by branching Cordyceps, which project from its head like a pair of antlers. But the largest of all these parasites grows on an enormous larva found on the banks of the river Murrumbidgee in Australia. It appears that species of Sphæriæ are parasitic on insects of very different affinities in China, America, and Europe. It may be presumed that, like the Cordyceps militaris, they are the ultimate development of fungi belonging to other families. [Illustration: Fig. 36. Sphæriacei:—Sphæria Desmazierii; _a_, ascus; _b_, sporidia; _c_, mycelium with conidia. Mucedines:—_d_, Botrytis curta.]