SECT. in. CORDYCEPS. 293 



scopic objects. Truffles prefer calcareous soil, and a tem- 

 perate climate. In England, they are found in Rutland- 

 shire, and numerous species grow in Northamptonshire, 

 but they are smaller than the continental truffles, which 

 increase in abundance and size towards the south, and 

 have their maximum in Italy, where they grow on the 

 roots of trees and vines, and are hunted by dogs, or 

 traced by the presence of a peculiar fly, and dug up for 

 sale. Sometimes the dogs dig them up, to the annoy- 

 ance of the proprietors of vineyards, from the mischief 

 they do to the roots of the vines. 



The Sphaeriacei, another order of Ascomycetes, are 

 enormously numerous. There are 1,000 well known 

 species of this order, and probably twice as many unde- 

 termined ; 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 har- 

 bour more than one species at a time. The genus Cordy- 

 ceps and many so-called species of Sphseria 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 Eobertsii, which grows like 

 a bunch of rushes from the head of the Hepialus vires- 

 cens of New Zealand; whilst a kind of wasp in the 



