PEZIZALES 



343 



a definite dehiscence zone (Fig. 228). During this development, the 

 ascogonium has been surrounded by sheath hyphae which, as no true 

 apothecium is formed, surround the apothecium like a peridium. The 

 unique character of Thelobolus stercoreus consists in that no ascogenous 

 hyphae are formed, but one cell of the female apparatus develops directly 

 to a single ascus. Perhaps T. stercoreus represents a degeneration series 

 like that of the Erysiphaceae in the Perisporiales. In this case, Thelobolus 

 stercoreus would correspond approximately to Sphaerotheca Humuli. 



Pezizaceae. — As we remarked in passing, the same degeneration takes 

 place in the Pezizaceae which we have followed in the Ascobolaceae. As 

 Lasiobolus br achy ascus in the Ascobolaceae is directly connected to 

 Pyronema confluens, so two forms of the Pezizaceae studied so far are in 

 close accord with this type, Lachnea stercorea and L. scutellata. 



t 



Fig. 228.— Thelebolus stercoreus. 1. Fructification in longitudinal section. The 

 sheath, h, is only partially shown; actually, it entirely surrounds the ascus, s; t is the 

 remnant of the ascogonium. 2. Mature fructification seen from above. (X 240; after 

 Brefeld.) 



Lachnea stercorea (Fraser, 1907; Fraser and Brooks, 1909) forms its 

 small, densely tomentose, orange fructifications, about 4 mm. in diameter, 

 on excrement of various animals, especially of cattle, during the winter 

 and spring. On any hypha a pyrif orm ascogonium with a long trichogyne 

 develops as a branch which is separated from the main hypha by several 

 stipe cells. The trichogyne is not unicellular, as in Pyronema confluens, 

 but is divided into 4 to 6 cells of which the terminal is the longest. An 

 antheridium, as in P. confluens, comes into open communication with the 

 trichogyne. In no case could a dissolution of the wall of the basal trich- 

 ogyne cell and migration of the male nucleus be proved. Probably, 

 as in certain nutritive conditions in P. confluens, the male nuclei 

 degenerate in the trichogyne, whereupon the ascogonial nuclei, after a 

 single division, pair autogamously and form ascogenous hyphae. Thus 

 the antheridium as well as the trichogyne is only vestigial. 



