General Features 7 



globular cell or oogonium surmounted by a tubular outgrowth, 

 the trichogyne, and attached to the mycelium b\' means of 

 basal stalk cells. The antheridia are produced in a similar 

 manner and are of about the same length as the oogonia but 

 much more slender. The trichog>ne at first grows upright but 

 later curves about and partially surrounds the top of the an- 

 theridium, finally fusing with it. A wall is formed at the base 

 of the trichogyne and about the same time the wall breaks down 

 at the point of fusion of the trichogyne with the antheridium. 



Fig. 3. Sex organs in Pyronetna from I)eBar\-. a, cluster of antheridia 

 and oogonia. b, ascogonium producing ascogenous hyphae, with antheridium 

 still attached. 



After the fusion of the trichog>ne with the antheridium the 

 oogonium, which now becomes the ascogonium, swells up and 

 produces outgrowths in a dozen places or more, which outgrowths 

 become the ascogenous hyphae and eventually give rise to the 

 asci. This is the process as described by DeBar\- (Fig. 3), 

 but it remained for later workers to add the cytological details. 



Both the oogonium and the antheridium are multinucleate as 

 well as the trichogyne. The nuclei of the latter later degenerate. 

 The nuclei from the antheridium graduall}' pass into the tricho- 

 gyne. Although there is some difference of opinion on this 

 point, it is generally conceded that the wall at the base of the 

 trichogyne now breaks down, permitting the male nuclei to pass 



