334 



COMPARATIVE MORPHOLOGY OF FUNGI 



The cell with a single dicaryon develops sidewise, with conjugate 

 division of its nuclei, in a hook-shaped process which was described in 

 the introduction to the Ascomycetes as a transitory hook tuft (Fig. 79), 

 and finally forms eight-spored asci. This tuft-like branching of the asco- 

 genous hyphae is one of the grounds for the conical widening which the 

 older fructifications of the Pyrenomemaceae and many other Discomycetes 

 often show. 



Already at the time of copulation the sexual organs are surrounded 

 by a loose layer of sheath hyphae. Later, these branch very much, 

 while the sexual organs are crushed and resorbed, and form the paraphyses 

 between which later the asci penetrate (Fig. 222). 



Fig. 221. — Pyronema confluens. Development of ascogenous hyphae. 1. The asco- 

 genous hyphae are aseptate and have numerous dicaryons. 2. Development of hooks. 

 (After Claussen, 1912.) 



In P. domesticum (Tandy, 1927) the first and often the third 

 division in the ascus is a meiosis; both diploid and tetraploid nuclei 

 being found in the young ascus. The development of this species follows 

 closely that reported by Harper for P. confluens. 



The sexual development of Pyronema is connected directly to that of 

 Monascus among the Plectascales. As there the female sexual apparatus 

 is divided into a unicellular ascogonium and an unicellular trichogyne, 

 and as there is a plurality of sexual acts, there follows a multiple plasmog- 

 amy between the male and female gametangial nuclei. It is nevertheless 

 characteristic of Pyronema confluens (and the Pezizales generally) that 

 its ontogeny can take place in this manner only when definite nutritive 

 relations occur. If these are absent, the antheridium still may be formed 



