iv] DISCOMYCETES 99 



differs in its multicellular trichogyne, and of Humaria granulata, and perhaps 

 some other forms in which the trichogyne, like the antheridium, has dis- 

 appeared. 



Another group is distinguished by the multicellular oogonial region of 

 the archicarp, which has also a stalk and a terminal region (or trichogyne) 

 of several cells each (fig. 58). This type of female 

 organ is sometimes termed a scolecite. It occurs 

 in Lachnea cretea and in several species of Asco- 

 bolus and Ascoplianus. 



In Ascobolus furfuraceus several of the central 

 cells communicate one with another by means of 

 pores, but only one of them gives rise to asco- 



y ° Fig 58. Ascobolus Jitrjui 



genous hyphae; in some other species of Asco- ivr'-..; archicarp, x; 4 o; after 

 bolus and in the genus Ascophanus ascogenous '"' ye ' 



hyphae arise from several communicating cells; the same is true of Lachnea 

 cretea, where three or four cells become practically continuous owing to the 

 disappearance of the transverse septa between them. 



In the trichogyne also, or terminal region of the archicarp, pores are 

 formed in the transverse walls, so that this multicellular organ offers no bar 

 to the passage of male nuclei. 



Such structures may well have been derived from the Ascodesmis type 

 by the elongation and transverse septation of the parts of the archicarp. 

 Our knowledge of the sexual organs of the Pezizales thus suggests that they 

 may have been derived, along two principal lines of development, from 

 a common ancestor within the group. 



In only two other families of Discomycetes, the Rhizinaceae (Rhisina 

 and Sphaerosomd) and the Geoglossaceae (Leotia) has an oogonium been 

 recognized. In each of these a large fertile cell is present, but its develop- 

 ment is not known and no suggestions as to phylogeny can therefore be 

 based upon it. 



Our knowledge of the development and especially of the reproductive 

 organs of the Discomycetes is still very incomplete and further research is 

 very necessary. As has been shown in Leotia, Humaria and other cases, it 

 by no means follows that because one member of a genus has lost its sexual 

 apparatus the same will be true of others. Every available species should 

 be investigated. 



The Discomycetes include over 4000 species and may be subdivided as 

 follows : 



Hymenium fully exposed at maturity 



mature ascophore cup-shaped Pezizai 1 



in. nine ascophore reflexed or stalked with the fertile 



region often convoluted 1 1 1 I VELLALES. 



7—2 



