446 



BOTANY 



PART II 



themselves side by side, and in the ascogenous hyphae divide conjugately, but 

 remain distinct from one another. The fusion of a descendant of a male nucleus 



FIG. 390. Pyronema confluen-s. A, Very young apothecium ; og, oogonia, with trichogynes (<) ; a, 

 antheridia (x 450). B, Fusion of the antheridium with the tip of the trichogyne (x 300). C, 

 The association in pairs of the male and female nuclei in the oogonium, which is cut trans- 

 versely ( x 1000). D, Passage of the paired nuclei into the ascogenous hyphae ( x 1000). E, Young 

 apothecium. The ascogenous hyphae springing from the oogonia have branched and are invested 

 by sterile hyphae (x 450). (B after HARPER. A, C, D, E after CLAUSSEN.) 



with the descendant of a female nucleus does not take place till the development 

 of theascus (Fig. 391). 



In many Discomycetes a reduction of the sexual organs has taken place 

 associated with a loss of sexuality. The antheridia are functionless or completely 

 suppressed, and in extreme cases the ascogonia are also wanting, only a tangle of 

 hyphae being recognisable in their position. The ascogenous hyphae in the 

 young fructification are, however, always present. 



The asci develop in various ways at the ends of ascogenous hyphae. As a rule 



