CLASS ASCOMTCETEAE 263 



stone of a stone fruit or raspberry, etc., and mykes, a fungus). It should be 

 noted that the basal groups of each of the three series include forms with 

 free, nonmotile sperms which come in contact with some receptive struc- 

 ture (trichogyne) and thus bring about fertilization. In the apothecial 

 series as well as in the perithecial series this gives place quickly to the 

 direct union of trichogyne and antherid and finally to the entire dis- 

 appearance of the trichogyne, and in many cases of the antherid also. 



Asexual reproduction probably reaches its highest degree of develop- 

 ment in this group of orders which may collectively be called the Pyreno- 

 mycetes, without necessarily indicating that they are at all closely related. 

 A very large proportion of the species have asexual reproduction by means 

 of conidia. The types of conidial production are most varied. Often sexual 

 reproduction is relatively rare, the conidia serving to maintain the species. 

 In many of the parasitic species the asexual mode of reproduction alone 

 occurs on the living host and the sexual stage is formed only on the dead 

 host tissues. The conidia may be produced on free conidiophores or on 

 conidiophores crowded in an acervulus or on conidiophores enclosed 

 within a pycnidium. In some cases all of these forms occur in the same 

 species of fungus at different stages of growth. Judging by the types of 

 asexual reproduction perhaps the majority of the so-called Imperfect 

 Fungi (Class Fungi Imperfecti) are probably conidial stages of the Py- 

 renomycetes, although possibly representing in many cases species that 

 have permanently lost their power of sexual reproduction. 



Studies have been made of the sexual reproduction in various forms of 

 the group but not only are there great numbers of genera in which studies 

 are lacking, but for many families no such studies have been made. The 

 results are conflicting for some of the supposedly related forms. The 

 stages of sexual reproduction are often difficult to find in a closely con- 

 nected series of development and it is usually with difficulty that they 

 can be satisfactorily sectioned and stained. This makes the interpretation 

 of the structures observed not at all easy and their interpretation is 

 naturally influenced by previously held views. So in describing the sexual 

 reproduction of various species the author has had to report the findings 

 as described and interpreted by the respective investigators although 

 this course involves some contradictions because of the different inter- 

 pretations by the various authors. Until many more forms have been 

 investigated, representing all of the more important genera and families, 

 it wnll be impossible to determine to what extent weight must be given 

 to this process in the classification of these fungi. 



A number of cases have been selected that show the various types of 

 structures concerned in sexual reproduction in the Pyrenomycetes, as 

 well as some of the special modifications of sexual behavior. In many of 

 these fungi spermogonium-like structures are known within which are 



