ORDER MYRIANGIALES 



333 



In ilf . duriaei Mont. & Berk, only one archicarp is formed in the young 

 ascocarp, the whole disk being the product of the divisions of its asco- 

 gonial cells and of the branching ascogenous hyphae arising from them. 

 In M. curtisii Mont. & Berk. 30 to 50 archicarps are produced and the 

 resultant ascogonia and ascogenous hyphae do not form as compact and 

 extensive a structure as in the other species. (Fig. 108 A-C.) 



The asci when mature have a two-layered wall. When the ascocarp is 

 wet by rain it becomes soft and the mature asci expand, pushing their 



Fig. 108. Myriangiales, Family Myriangiaceae. 

 (A-C) Myriangium duriaei Mont. & Berk. (A) 

 Stroma, top view; the cuplike bodies are asco- 

 genous. (B) Ascus. (C) Dehiscing ascus, the outer 

 wall ruptured and the inner wall elongated but 

 still intact. (D, E) Elsinoe veneta (Speg.) Jenkins. 

 (D) Vertical section of ascocarp. (E) Acervulus 

 (Sphaceloma) stage. (A-C, after Fetch: Brit. 

 Mycol. Soc. Trans., 9:45-80. D-E, after Burk- 

 holder: Cornell Agr. Expt. Sta. Bull., 395:155-183.) 



tips through to the surface. The outer ascus wall splits and contracts 

 around the base of the ascus while the thin-walled inner layer pushes out 

 further and discharges its eight greenish yellow muriform ascospores a 

 distance of several centimeters. The lower asci push up through the spaces 

 left by the disappearance of the upper asci and repeat the process. There 

 is no weathering away of the tissues as previously believed. The ascocarps 

 of the other genera usually placed in the same family with Myriangium 

 have not been given sufficiently intensive ontogenetic study to make it 

 certain that they have the same type of development although that prob- 

 ably is so. Apparently the asci in these other genera are of the same type 

 as those o" Myriangium. 



