588 Scientific Proceedings, Royal Dublin Society. 



Fig. 4. An early stage in the development of an oogonium ; no antheridium is 

 present. (Quaker-Oat agar.) 



Fig. 5. A " twin"- oogonium in whicli two oospores would probably have been 

 formed. A distinct wall separating the oogonium from the hypha which 

 bears it is present in this case. (Quaker-Oat agar.) 



Fig. 6. An oogonium containing a young, parthenogenetically formed oospore. 

 The lower limit of the wall of the oogonium is clearly seen, but there 

 is no septum closing off the oogonium from the hypha which bears it. 

 (Quaker-Oat agar,) 



Fig. 7. An oogonium borne laterally on a hypha and containing a young pear- 

 shaped oospore, formed parthenogenetically. (Quaker-Oat agar.) 



Fig. 8. An oogonium (containing a practically ripe oospore) with its lower portion 

 within an antheridium. The hyphae at the base of the antheridium 

 are probably the oogonial and antheridial hyphae ; but it was impos- 

 sible in the preparation to determine this with absolute certainty. 

 05f = oogonium, os = oospore, «?i = antheridium. (Quaker-Oat agar.) 



Fig. 9. An oogonium (with a practically ripe oospore) with its antheridium. The 

 antheridium is probably a terminal structure borne on the hypha a ; the 

 funnel-shaped lower portion of the oogonium, within the antheridium, is 

 probably continuous with the hypha o (at the back) ; but the connection 

 could not be made out with absolute certainty. (Quaker-Oat agar.) 



Fig. 10. An oogonium (with a practically ripe oospore) with its lower portion 

 within the antheridium, which is a sessile structure on the hypha aa. 

 The hypha bearing the oogonium was broken off during the removal 

 of the adhering medium. (Quaker-Oat agar.) 



Figs. 11 and 12. Oogonium, oospore, and antheridium. The irregularities in the 

 oogonium wall are indicated by shading (except over the oospore). In 

 fig. 11 the antheridium is probably a lateral outgrowth of a hypha, the 

 end of which is seen at a, the other portion of it being absent, o is 

 the hypha which bears the oogonium, and it was definitely traced into 

 the antheridium and seen to be continuous with the funnel-shaped base 

 of the oogonium. In fig. 12, the antheridium is a terminal structure, 

 borne on the hypha a ; and its contents are represented somewhat 

 contracted away from its walls, o is the hypha bearing the oogonium ; 

 its passage into the antheridium and continuation as the funnel-shaped 

 base of the oogonium were clearly discernible, m is a small portion of 

 adhering medium. (Quaker-Oat agar.) 



