ORDER SPHAERIALES 273 



under the older systems of classification were confidently placed in one or 

 another of these three orders, have been found to possess structures that 

 are not true perithecia and so have had to be removed to other orders. 

 Many more have not been studied from this standpoint and are still kept 

 in their customary position but some of these, too, will probably have to 

 be transferred. In the following, where it seems probable that whole 

 families should be transferred, that has been done but in cases of doubt 

 where only a few genera have been carefully studied the old classification 

 (that of Lindau in Engler and Prantl, 1897) is retained. 



The term paraphysis has been used differently by various students of 

 the Pyrenomycetes. Theissen, Sydow, and perhaps the majority of 

 mycologists, including the author, define as paraphyses those slender 

 hyphae that develop in the hymenium, growing up from below and ending 

 free above. In between them arise the asci to which they give protection 

 and perhaps nourishment. In some groups of Discomycetes, e.g., various 

 genera of Tuberales and Lecanorales, these paraphyses may enlarge and 

 branch above the asci and grow fast to the enlargement or branches of 

 other paraphyses to form a more or less continuous pseudoparenchyma- 

 tous layer over the tips of the asci, the epithecium. In the Pseudosphae- 

 riales the sheets of more or less crushed stromatic tissue that remain 

 between the developing asci and which may be reduced to interascal 

 hyphae, attached to the base of the hymenium and the roof of the asco- 

 carp are called by Petrak (1923) true paraphyses while he uses the term 

 metaphyses for the structures called paraphyses by Theissen, etc. The 

 term paraphysoid is used with various meanings by different mycologists. 

 By some it is applied to the filamentous often deliquescent remains of the 

 stromatic tissue between the asci (the true paraphyses of Petrak) while 

 by others it is applied to quickly evanescent true paraphyses. 



Order Sphaeriales.^ This order is described first not from any convic- 

 tion that it is more primitive than the other two but because it offers a 

 better field in which to point out the various developmental directions in 

 the modification of the perithecia. The perithecial wall is in general dark- 

 colored, at least in its outer stromatic layer, pseudoparenchymatous in 

 structure and free from the enclosed asci which arise from its base or part 

 way up its sides. Sometimes the asci form a dense hymenium but fre- 

 quently they are more loosely arranged. Paraphyses may be present but 

 are usually delicate and evanescent and not very numerous. When true 

 paraphyses are absent the suspicion is aroused that perhaps these organ- 



' It should be noted that this name and that of the family Sphaeriaceae are not 

 properly valid since the generic name Sphaeria has been entirely abandoned because 

 of its former application indiscriminately to fungi with conidia (i.e., without asci) 

 and perithecia. Rather than to propose a new set of names the old familiar ones are 

 retained here. 



