Coker: Achlya DeBaryana Humphrey 323 



diameter of the oogonia. The walls of the oogonia are generally 

 quite round and smooth, but at times they are furnished with low 

 rounded projections at the pits, which are scarcely larger than to 

 make the oogonia appear angular in section (fig. 9). In the walls 

 of many oogonia pits are obviously present at pretty regular dis- 

 tances (fig. 10), but in many others the wall appears to be free 

 of pits except that it is thin over the whole extent that is covered 

 by the antheridia (fig. 11). Intercalary oogonia appear occa- 

 sionally as shown in fig. 12. The oospores are eccentric and are 

 very variable in number. Two, four, and six are common num- 

 bers, one and eight are not rare, but more than eight are not often 

 seen. 



The antheridial branches arise from the same main hyphae as 

 the oogonial branches. They usually extend for a considerable 

 distance, branching either extensively or sparingly, and attach 

 themselves to any oogonia they may meet, whether from their own 

 main hyphae or from others. However, they seem to show some 

 preference for the oogonia of other hyphae, and the antheridia on 

 an oogonium are more apt to be of diclinous than of androgynous 

 origin. This agrees with what Horn found in his plants, as 

 mentioned above, and is contrary to DeBary's observations on his 

 Achlya polyandra (A. DeBaryana Humphrey). In fig. 13 is 

 shown an antheridial branch which has arisen by the proHfera- 

 tion of a halted oogonial initial, thus showing the essential homol- 

 ogies of the two sorts of organs. This branch has furnished 

 antheridia for two oogonia of the same origin as itself. Not al] 

 oogonia are furnished with antheridia, the number without them 

 varying from a small to a rather large proportion in different 

 cultures. 



It is now evident that our Chapel Hill form cannot certainly be 

 referred to any described species of the proUfera group. If we 

 compare their characters it would seem that our plant is some- 

 what nearer A. prolifera than it is to the others, as the antheridia 

 are most often of diclinous origin, and the oogonia are generally 

 pitted. But as A. prolifera, according to DeBary, does not have 

 antheridia and oogonia on the same main hypha, that species is 

 excluded here. And A. DeBaryana as described by DeBary (as 

 A. polyandra) is equally excluded by its lack of oogonial pits and 



