FUNGI. 267 



from the Sclerotium as a base. We have no know- 

 ledge of this particular fungus, except when springing 

 from such a compound mycelium. Other species of 

 Pesi:::a are developed from other forms of Sclerotium. 

 In the case of ergotized grain (Fig. 53, a) the ovary is 

 converted into a compact Sclerotium, which undergoes 

 a period of rest, perhaps of some months, and then 

 develops a spha;riaceous fungus called Claviceps pur- 

 purea. The ergot is now regarded as the hibernating 

 mycelium of the more complete fungus Claviceps, and 

 every ergot is held to be capable, under favourable 

 conditions, of developing one, two, or more of the 

 little pin-headed fungus. Cultivators of mushrooms 

 are painfully aware of the production of a black 

 Sclerotium in great numbers on their mushroom beds, 

 to the great detriment of their special cultivation. 

 These black bodies undergo a resting period, which 

 may extend through the winter, and are in reality the 

 hibernating stage oiXylaria vaporaria} (Fig. 54), which 

 latter may be cultivated artificially from the Sclero- 

 tium by placing it in damp sand. The quiescent 

 condition is developed in autumn, whilst the perfect 

 state may be looked for in the succeeding March or 

 April. The only other example which we purpose 

 to allude to is one in which the Sclerotium is pro- 

 duced in great numbers on old potato haulms, from 

 the size of a grain of sand to that of a small bean. 

 After a period of hibernation, and then chiefly by 

 artificial culture, a small Peziza is obtained, growing 

 from the sclerote. Although at first considered a new 

 species, it was afterwards determined to be one which 



* Linn. Trans., xxiv. t. 25, figs. 17-26. 



