ETTER: POLYEMBRYONY IN POLYPODIACEOUS FERNS 105 
larger one, B, which, however, soon outstripped the older in 
development. The whole was transplanted, and four months 
later, at the time of this writing, both sporophytes are still 
growing but B is far in advance of A. 
TEXT FIG. 7 shows two widely separated embryos of Mattenccia 
Struthiopteris, each one near a sinus of a regenerated part, both of 
which came from one half of the previously divided prothallium. 
Both sporophytes appeared about the same time and developed 
slowly, although about equally, as illustrated. This sort of occur- 
rence was not as common as that in which only one part was 
regenerated, yet several instances like this were observed. At 
this time it is impossible to say just what the nature of the devel- 
opment of the archegonial cushion is, but we are inclined to the 
notion that the original cushion has simply branched, and that 
therefore both sporophytes are located on one cushion instead 
of on two independent and remote archegonial cushions. The 
condition illustrated by TEXT FIG. 7 was more common among 
gametophytes of Dryopteris mollis than among any other species 
studied. 
A few prothallia were quartered by dividing the prothallium 
longitudinally and then at right angles to the first cut through 
the archegonial cushion. In one instance one quarter started a 
sporophyte within a few days. Two of the remaining quarters 
regenerated new normal prothallia, each of which brought a 
sporophyte, and one of these also produced a sporophyte on the 
older part. The remaining quarter produced two new prothallia 
which in turn developed two sporophytes. In another instance 
two of the quarters regenerated new normal prothallia from 
which sporophytes came; the remaining two proliferated quite a 
number of prothallium-like forms, from which no sporophytes 
had developed at the time of this writing. 
SUMMARY 
Polyembryony in Matteuccia Struthiopteris, Onoclea sensi- 
bilis, Dryopteris mollis, and Pteris longifolia may occur, though 
not frequently, in ordinary cultures and perhaps in nature. 
Under experimental conditions two to several embryos may 
be made to develop on a gametophyte of the above named 
species. 
