CHAPTER V. — COMPARATIVE REVIEW. — ASCOMYCETES. 



187 



later page, require a more searching investigation. But even if there are some 

 exceptions to the rule, and a good many cases require further examination, the 

 prevailing rule undoubtedly is that the two constituents of the sporocarp though 

 close to one another are independent in their origin and growth. 



Eremascus, a typical Ascomycete of the simplest form, recently described by 

 Eidam, is remarkable for the entire absence of an envelope-apparatus. 



Three chief forms of sporocarp in Ascomycetes may be distinguished according 

 to the arrangement and conformation of its two constituent parts, and the coarser 

 structure which results therefrom : the discocarp or apothecium and the pyretiocarp 

 or perithecium, which are used to distinguish the Discomycetes from the Pyrenomycetes, 

 and the cleistocarp, a form which remains closed. I use the words apothecium 

 and perithecium in the sense introduced by P. A. Karsten in his Mycologia fennica. 



*-> 



FIG. 86. A Usneabarbata. B Sticta pnhnonacea. Portions of thallus. a apothecia,./ point of attachment to the 



substratum. After Sachs. Natural size. 



There are a few forms or small groups which cannot in strictness be arranged 

 under one of these three types, but must be placed along with them as peculiar 

 and exceptional cases. The accounts which we possess of the history of the 

 development, though imperfect, 'are sufficient to show that the above types are 

 distinguished more by habit in their advanced states than by any more fundamental 

 distinction. 



Section LX. The distinguishing feature in the apothecium. (Figs. 86-89, see 

 also Figs. 19, 22, 85, and 99) is, that the hymenium lies exposed on the surface 

 of the sporocarp while the spores are forming and maturing. The hymenium 

 itself, the discus, lamina proligera and sporigera of the old terminology, consists 

 first of the asci, secondly of capilliform hyphal branches, the paraphyses. The 



