328 COMPARATIVE MORPHOLOGY OF FUNGI 



arranged in a palisade and develop to paraphyses. By the pressure of 

 the growing paraphyses, the sheath is ruptured, allowing the apical por- 

 tion to project. Finally the ascogenous hyphae push from the ground 

 tissue and form asci. In certain species, e.g., Cudonia lutea, the tearing 

 of the veil may come very late when many asci are already mature. 



The sexual organs of the Geoglossaeae undergo a peculiar degenera- 

 tion, such as we shall meet again in the Lecanoraceae-Cladoniaceae 

 (Icmadophila-Baeomyces) series. As in the latter, the ascogonia do not 

 arise directly from vegetative hyphae but from a loose tangle of densely 

 staining hyphae, the so-called generative or primordial hyphae. 



In the first stage, as in Leotia gelatinosa (L. lubrica), they form one (or 

 several) ascogonia at the base of the fructification (Dittrich, 1902; Brown, 

 1910, Duff, 1922) very early, when the fructification is a small, undif- 

 ferentiated tangle. Nothing is known of their form. It was observed, 

 however, that from a single large cell, the ascogenous hyphae develop 

 pari passu with the elongation of stipe and finally form asci between the 

 paraphyses. In analogy to the Operculatae, one may assume that this 

 one large cell is the privileged sexual cell of the ascogonium and that the 

 sexual act is probably parthenogamous. 



In the second stage in Cudonia lutea, the formation of ascogonia is 

 retarded. Here the generative hyphae are early differentiated before 

 the volva is formed. They remain inactive, however, in the apical zone 

 of the fructification several cell layers below the later paraphyses and are 

 raised by the central hyphae, on the elongation of the fructification. At 

 a given time, they grow out into the ground tissue of the head and form a 

 large number of slightly curved or helical, at first uninucleate, later multi- 

 nucleate ascogonia which open out into typical multicellular trichogynes; 

 these penetrate the veil and project a distance into the open but degener- 

 ate early. Antheridia are lacking ; the nuclei in the ascogonia are arranged 

 in pairs and migrate into the ascogenous hyphae. Thus the sexual 

 processes are autogamous. 



In Spathularia velutipes, not only the formation of ascogonia, but also 

 that of generative hyphae is retarded, and they only appear when the 

 fructification attains a considerable size; here also they lie directly under 

 the tip and, as in Cudonia lutea, develop to ascogonia. These are morpho- 

 logically quite degenerate, however, and no longer possess trichogynes 

 (Fig. 218, 1); they differ from the usual vegetative hyphae of the hypo- 

 thecia only in their greater cross section and deeper staining. Their 

 nuclei also pair and migrate into the ascogenous hyphae. 



Finally, in the fourth stage, in Trichoglossum hirsutum, the sexual 

 organs are no longer morphologically recognizable as such. Neither 

 generative hyphae nor ascogonia are formed and the ascogenous hyphae 

 develop in some unknown manner from any vegetative hyphae rich in 

 protoplasm. 



