PEZIZALES 



351 



migrates to the ascogonium, which subsequently develops ascogenous 

 hyphae (Baur, 1898). 



In Collema pulposum or a closely related species, a different behavior 

 has been determined. Here the conidia, as in Ascobolus carbonarius, 

 do not fall away but remain on the conidiophores. Hence the trichogyne 

 grows, as in Ascobolus carbonarius, over the thallus surface toward the 

 conidiophores and unites with them (Fig. 236). In these lichens the more 

 migration of the conidial nucleus into the trichogyne has been demon- 

 strated; the nuclear relationships in the ascogonium are so complicated, 



Fig. 236.- — Collema pulpostim. Trichogyne growing toward conidiophore. ( X 345; after 



Bachman, 1912.) 



however, that their further fate cannot be followed (Bachman, 1912, 

 1913). 



Because of this property of copulation with trichogynes, the conidia 

 of lichens have been considered specialized male sexual cells and called 

 spermatia and the pycnia correspondingly have been called spermagonia. 

 Moeller (1887, 1888) and Istvanffi (1895) working with impure cultures 

 have denied the assumption of this specialization, as the pycnidiospores 

 may develop in culture to mycelia, as normal imperfect forms. More 

 probable is the interpretation which already has been brought forth 

 in connection with Ascobolus carbonarius; that it is a question of ordinary 



