Brown: Apogamy in Phegopteris polypodioides 23 



the unmodified Prantl's and Knop's solutions, while only 

 dioecious prothallia were observed in the greenhouse cultures 

 on the same solutions. In the younger cultures, those not more 

 than six or eight weeks old, the majority of the prothallia were 

 dioecious, the percentage of monoecious individuals being very 

 low even in cultures on the modified solutions. Among older 

 prothallia it was not infrequent to find monoecious specimens, 

 the antheridia developing on or near the margin of the larger 

 heart-shaped prothallia. Antheridia were never observed on the 

 cushion, among the archegonia, as is the case in typical monoe- 

 cious prothallia. The percentage of male prothallia was much 

 higher than that of female, as is usually the case on the modified 

 solutions. While many of the male prothallia were mere fila- 

 ments of from one to three cells in width bearing antheridia, 

 there were also a large number of small irregularly-shaped cell- 

 plates one cell in thickness, bearing antheridia over both the 

 upper and lower surfaces. The antherozoids in all the cultures 

 appeared normal. The majority of the larger prothallia on 

 the modifiedsolutions were more or less heart-shaped, without 

 a sinus but with a well-developed meristem upon which ar- 

 chegonia were formed. Evidently these were not functional, 

 as no normal sporophytes developed. In rare cases a few an- 

 theridia were formed from the marginal cells of the prothallia 

 which developed the apogamous outgrowths and sporophytes. 



Description of thf apogamous outgrowths and 

 sporophytes 



In the first observed cases of apogamy the prothallia bear- 

 ing the apogamous sporophytes were irregularly heart-shaped, 

 with a well-developed meristem. Archegonia were formed on 

 some of the prothallia, but not antheridia. The apogamous 

 sporophytes, in all these cases, originated as slight swellings 

 of the archegonial cushion, either on the dorsal or ventral side, 

 at some point near the notch or at the center of the cushion. 

 These swellings gradually increased in size until dome-shaped 

 cellular masses were formed, from which the parts of the 

 apogamous sporophytes appeared in the following order: 

 leaf or leaves, root, and stem. No foot was formed. In some 

 cases proliferations, either filamentous or slightly expanded at 

 the apices, developed from the cellular mass. Also, multicellular 



