220 CLASS ASCOMYCETEAE 



colony it inhabits. There is no cortical layer. On the interior mycelium 

 there arise here and there somewhat thicker hyphae which are noticeable 

 because of their dense contents and more or less loosely coiled structure. 

 These are the ascogonia. The cells like those of the vegetative mycelium 

 are uninucleate. Each ascogonium consists of from one to three coils of 

 cells terminated by a filament (the trichogyne) which turns toward and 

 projects just through the surface of the colony. Its exposed tip is sHghtly 

 enlarged and covered with a somewhat thickened wall which is sticky 

 when Avet. In its multicellular structure it differs greatly from the tricho- 

 gyne of the Florideae. The male organs are branched hyphae projecting 

 into a conceptacle-hke spermogonium which opens at the surface of the 

 colony. From these branches there bud off minute, uninucleate, non- 

 motile sperms possessing a delicate cell wall. When wet by rain the gummy 

 mass filling the spermogonium swells and oozes from the opening, where 

 the gum dissolves and the sperm cells are floated off by the film of rain 

 water. Such a sperm coming in contact with the sticky tip of the tricho- 

 gyne adheres to it. Stahl (1877) and Baur (1899) have demonstrated that 

 an opening is dissolved quickly through which the sperm nucleus enters 

 into the apical trichogyne cell. Successive swellings and disappearance 

 of the septa of the trichogyne seem to indicate the passage of the sperm 

 nucleus down to the coils of the ascogonium. The nuclear behavior has 

 not been followed in detail however. From one of the ascogonial cells, 

 which therefore corresponds in function to the oogone of Pyronema, asco- 

 genous hyphae begin to grow outward and upward. The surrounding 

 vegetative hyphae also become actively involved in growth and produce 

 the vegetative part, including the paraphyses, of the apothecium. The 

 ascogenous hyphae produce their asci by the hook method as described 

 for Pyronema. It should be noted that in some genera of lichens the sperm 

 cells, or cells resembling them and produced in similar conceptacles, are 

 capable of growing in pure culture in nutrient media until normal thalli 

 are produced bearing similar conceptacles. This was reported by Moller 

 in 1887. He obtained thalli by culturing such cells from Buellia puncti- 

 formis Hoffm., Opegrapha suhsiderella Nyl., 0. atra Pers., Arthronia sp., 

 Calicium parietinum Ach., and other species of Calicium. He also cul- 

 tured the conidia from the pycnidia which in some cases are present in 

 the same thallus. He therefore drew the conclusion that the spermogonia 

 as well as pycnidia were both asexual reproductive structures and that 

 the supposed sexual function of the spermatia was erroneous. (Fig. 73A, 

 B, D-G.) 



Miss Bachmann (1912) erroneously identified the very similar lichen 

 Collemodes hachmannianum Fink with Collema pulposum (Bernh.) Ach. 

 She found that in Collemodes the branches which produce the sperm cells 

 are not produced together in spermogonia but are scattered here and 



