376 



FUNGI 



FIG. 310. Ear of rye with two 

 mature sclerotes (ergot) of 

 Claviceps purpurea> (natural 

 size). (After Luerssen.) 



borne on the summit of a stalk arising from a 

 sclerote (the well-known ergot of grasses) ; the 

 ascospores are filamentous in form, and on 

 germinating produce hyphae at several points. 

 When this takes place under suitable circum- 

 stances on the pistil of grasses, the tubes enter, 

 and, besides penetrating the tissue, form at 

 length a white hymenium on the surface. This 

 hymenium consists of numerous cylindrical ste- 

 rigmata, which bear acrospores at their apices. 

 (This stage was described by Leveille by the 

 name of Sphacelia.) These are given off in 

 drops of a sugary juice which oozes out be- 

 tween the flower-leaves in which the pistil lies. 

 This juice, ' honey-dew,' is eaten greedily by 

 insects, which doubtless eat the acrospores with 

 it. These propagate the Sphacelia state. At 

 the base of this acrospore-forming body the 

 formation of the sclerote proceeds, and it ulti- 

 mately replaces the ovary, emerging from the 

 flower of the grass with its base seated on the 

 floral receptacle. It gives rise in turn to the 

 sporocarp again. 



The allied genera Cordyceps (Fr.) and 

 Epichloe (Fr.) agree with Claviceps in the de- 

 velopment of the sporocarp. 



Besides the above distinctly marked types,, 

 the origin of the sporocarp and the life-history 

 of a considerable number of other forms have 

 been more or less completely investigated. It 

 would be entirely beyond the proportions of 

 the present book to enter into a description 

 of these, and a discussion of the controversies 

 that are bound up with the accounts of the 

 multitude of incompletely known forms. The 

 citation of the literature at the end of this 

 section will guide the student to original papers, 

 but he may also be referred here, as in so many 

 other cases of difficulty, to de Bary's ' Compara- 

 tive Morphology and Biology of Fungi,' &c., 

 1887, as containing ah exhaustive and critical 

 treatment of these more or less obscure forms. 



