264 BOTANICAL GAZETTE [APRIL 
Among other Filicales this feature of embryonic selection is 
likewise to be found. Mark te has prepared many slides of fern 
embryos in order to supply them for school use, and is therefore 
able to speak from considerable experience. Most of his material, 
which includes a variety of leptosporangiate species, was obtained 
from greenhouses. He has found that by carefully examining his 
sections in the paraffin ribbons before fixing them to the slides, he 
has usually been able to make more than one good preparation 
showing a one-,a two-, or a four-celled embryo on a slide, out of the 
ribbon obtained from a single large gametophyte. MARKLE 
states in a letter: 
I do not think I have ever seen more than one embryo on a gametophyte 
where each had reached the stage with the first leaf evident. I have, however, 
seen a number of instances where there were at least two or three, possibly 
four embryos in the two-celled or four-celled stage on one gametophyte. 
In sectioning material in which the largest embryo was in the stage where 
the four quadrants have their respective primary organs (foot, root, stem, leaf) 
well organized, I have seen other small embryos, very evidently suffering from 
the competition and losing out in the fight with the larger embryos, as was 
shown by the shrunken appearance of the cells. 
Among the fern gametophytes of the preceding discussion, 
there are quite a few instances in which the several embryos are 
only those of the somewhat independent or 
remote archegonial cushions. For example, 
Angiopteris evecta (fig. 23) and Vittoria (fig. 21) 
both have the young sporophytes some distance 
removed from each other. This condition is 
found among ferns having large or branching 
gametophytes, which may have several arche- 
Fic. 23—Gameto- gonial groups more or less remote from each 
phyte ry Angiopteris other. Among these, as well as among the 
ferns with large tuberous gametophytes, there 
after FARMER (18). is active embryonic selection only when two or 
more neighboring archegonia are fertilized. 
Likewise among leptosporangiate ferns the polyembryony has great- 
est significance when the competing embryos are near each other, 
as when they are on the same archegonial cushion. This form of 
embryonic selection, like that of conifers, only rarely produces 
