ASCOMYCETES 761 



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envelope, which are unconnected with each other though interwoven 

 in the hypothece, may be traced down to the apparently uniform tissue 

 of the stalk. De Bary thinks, however, that these may have a distinct 

 origin — the ascogenous hyph^e in those proceeding from the original 

 coil formed in the sclerote, and the envelope-hyphae in others springing 

 with them from the sterile tissue of the sclerote — that the coil in fact 

 may be (or may contain) a carpogone, though there is no sign of 

 antherid or pollinoids. The tracing of the continuity of these hyphae is 

 impossible throughout the long stalk with its uniform tissue. With this 

 type are to be classed the lichen-fungi investigated by Krabbe(Sphyridium, 

 Flot., Bccomyces, Pers., and Cladonia, Hill) the sporocarps of which 

 exhibit a clear distinction between ascogenous and envelope hyph^ from 

 an early stage. The former, however, have not been traced to a carpo- 

 gone or other special initial organ, and neither antherid nor pollinoid 

 has been discovered. Such genera as Claviceps, Epichloe, Pleospora, &c., 

 in which all that has been observed is a gradual specialisation of uniform 

 hyphae to the functions of ascogenous and envelope hyphce follow this 

 last type as the farthest removed from those forms described under the 

 second type. 



Course of Development. 



Within this large class several more or less distinct types of the 

 course of development may be recognised. Just as in the case of the 

 origin of the sporocarp, Ereinascus albiis is among the simplest of all. 

 This remarkable type (the sporocarp of which is destitute of envelope- 

 tissue) possesses no other reproductive bodies than the ascospores pro- 

 duced in the single ascus which represents the sporocarp. That is to 

 say, the germinating ascospore gives rise to a thallus which directly bears 

 the sporocarp again. In the same case are also the Collemaceas with 

 probably all lichen-fungi, and Pyronema, Ascobolus, Gymnoascus, H^-po- 

 copra, and Sclerotinia sclerotiorum, which last, however, possesses other 

 propagating bodies in the shape of mycelial resting-cells comparable with 

 the soredes of hchens. Another type (to which Sclerotinia Fuckeliana, 

 de By. and Wor., belongs) is but one remove beyond this, since the 

 life-history may go directly from sporocarp to sporocarp, though in the 

 typical state acrospores intervene. Here the germinating ascospore 

 gives rise to a thallus which bears acrospores, or, as has been said, the 

 sporocarp again ; though never both together or successively on the same 

 thallus. The germinating acrospore in turn produces a thallus with 

 precisely the same properties and capabilities as that arising from the 

 ascospore, except that in some cases there appears to be a tendency to 



