112 



ASCOMYCETES AND RHODOPHYCE^E. 



and a number of stalk-cells is usually to be distinguished at the 

 base of the antheridium. With further development the papilla or 

 young conjugating-tube elongates rapidly, its tip curving somewhat 

 to meet the end of the club-shaped antheridium which curves slightly 

 over the oogonium, frequently exceeding the latter in height (Fig. 

 41, C). At first the contents of the trichogyne and the oogonium are 

 continuous (Fig. 41, B). It is multinucleate, and the nuclei do not 

 appear to be diffei'ent from those of the oogonium. Long before the 

 trichogyne becomes fused with the antheridium, a cross-wall is formed 



A 



C 



FIG. 41. Development of sexual organs in Pyronema confluent. (After Harper.) 



A, young pair of sexual organs with several vegetative cells below. 



B, older pair, trichogyne not yet delimited from oogonium ; antheridium cut transversely, hence seen 



in transverse section. 



C, oogonium and antheridium in longitudinal section ; oogonium stalk with budding vegetative hyphse ; 



trichogyne with hyaline beak, its nuclei swollen and transparent. 



at the juncture of the tube with the oogonium, delimiting it from the 

 latter. This wall is formed before the sexual cells or the trichogyne 

 have reached their mature size. Whether nuclear divisions occur in 

 the tube after it is cut off was not determined (Fig. 41, C). During 

 subsequent growth the nuclei in the trichogyne do not increase in size 

 as do those of the antheridium and oogonium, but sooner or later show 

 signs of disintegration. They swell up without an increase of their 

 contents until they may equal in size the sexual nuclei, but they are 

 very transparent. Later, during the formation of the fusion-pore 



