io6 



DISCOMYCETES 



[CH. 



In any case the greater part of the male cytoplasm does not enter the 

 oogonium but is left behind in the antheridium and trichogyne ; con- 

 sequently these organs, after their function is complete, remain, to the 

 superficial view, unchanged for a long period, till they are crushed at last 

 by the growth of the investing hyphae, or perhaps destroyed by bacteria 

 (Harper, p. 354). 



Before the stages described above, the oogonium has begun to bud out 

 (fig. 6~2a) at various points, giving rise to the ascogenous hyphae. Into 

 these the nuclei pass, a few, no doubt unpaired, being left behind in the 

 oogonium. The hyphae elongate, branch freely and undergo septation, and, 

 as the vegetative filaments grow up, they ramify among them and at last 

 bend over and give rise to asci from their penultimate cells. Claussen has 

 described a paired arrangement of the nuclei in the ascogenous hyphae 

 (fig. 63*:), and believes the members of each pair to be respectively male 

 and female. 



After the ascogenous and vegetative hyphae are thoroughly interwoven, 

 a rapid stretching upward of the whole mass ensues. In this growth the 

 vegetative hyphae outstrip the reproductive ones, and form at first a cone- 

 shaped mass, made up of their elongated, slender, densely aggregated tips. 

 These upper extremities of the vegetative hyphae are the young paraphyses. 

 Their number is constantly increased by the pushing in of new branches 

 from below, and thus the conical outline of the mass is maintained. The 

 ascogenous hyphae grow for a certain distance in company with the 

 vegetative filaments, then their upward growth ceases, and they spread out 



horizontally, forming a rather dense layer 

 below the cone of paraphyses. This is the 

 base of the hymenium. 



Usually in Pyronema, as in Ascodesmis, 

 several oogonia are invested by a common 

 sheath, and their ascogenous hyphae mingle 

 to form the hymenium of a single ascocarp 

 (fig. 64), but ascocarps developed in relation 

 to a single pair of sexual organs are not 

 unknown. 



The formation of the asci in Pyronema 

 is quite typical. The number of chromo- 

 somes is probably ten (Harper), or twelve 

 (Claussen), at any rate in the first divisions 

 in the ascus. Dangeard records a smaller 

 number in the third division, and in the 

 variety inigneum Brown describes five 

 throughout. 



Fig. 64. Pyronema conjliiens; diagram- 

 matic section through ascocarp ; after 

 Harper. 



