1910] PACE—FERN PROTHALLIA 53 
’ Fertilization 
A few prothallia were placed in water for a short time, and fer- 
tilization took place in the usual way, one or more sperms entering 
the neck and reaching the so-called receptive spot, where one sperm 
enters the egg. The sperm nucleus fuses slowly with the egg nucleus, 
Fics. 7, 8.—Fig. 7, antheridium with spermatogenous cells in mitosis, showing 
approximately 16 chromosomes; fig. 8, antheridium with sperms almost mature 
the fusion apparently being completed while both are in the resting 
condition. A few normal embryos in well-advanced stages were 
found. These must have been formed from the fertilized egg or 
have been developed parthenogenetically. 
Apogamy 
A peculiar structure was found on the gametophyte which bore 
the antheridia shown in fig. 8, but it was found on the upper surface. 
The diagram (fig. 10) shows the relation of this body and the anther- 
idium to each other and to the archegonia. It is clear that there are 
only two possible interpretations of this structure: it must be an 
