Allen—Spermatogenesis and Apogamy in Ferns. 7 
vascular bundle may form running the length of the prothal¬ 
lium. A “middle lobe” may grow out from the apical meri- 
stem. Transitions are found between middle lobes and normal 
first leaves. Some of these have stomata and tracheids. 
In addition to this description of Pteris cretica, De Bary 
gives the first account of Apogamy in Aspidium felix-mas var. 
cristatum and in Aspidium falcatum. The process in essen¬ 
tials is the same as in Pteris cretica. In Aspidium falcatum 
archegones are found on twenty-five to thirty per cent of the 
prothallia but they do not open and they cease to form when 
the sporophyte develops. The apogamous shoot forms as in 
Pteris, but its surface is sometimes irregular. The root is 
often very late in forming. There are very few abortive sporo- 
phytes in Aspidium falcatum. Secondary prothallia some¬ 
times form. 
Leitgeb (66) (1885), studied the light reactions of Apoga¬ 
mous fern prothallia. If a prothallium of Aspidium falcatum 
bearing a very young sporophyte is lighted on the ventral side, 
the sporophyte is suppressed and a new one forms on what has 
been the dorsal side. In rare cases both survive and they ap¬ 
pear to form one sporophyte with its members on both sides of 
the prothallium. Leitgeb explains some of the anomalies 
described by de Bary as due to alteration of light relations 
during the growth of the prothallia. 
Bower (20) in 1888 reports a further case of Apogamy ac¬ 
companied by apospory in 'Trichomanes alatum. Spores are 
commonly produced in this species but on old fronds that lie 
on the ground, aposporous prothallia form freely. The gameto- 
phyte, which consists of alternating protonema-like filaments 
and flat one-layered cell masses or ribbons, bears gemmae and 
antheridial sacs but no archegones. On this prothallium 
sporophyte buds may form either on the end of a filament or 
sessile at the margin of a ribbon or on its surface. The transi¬ 
tion between the gametophyte and sporophyte tissues is some¬ 
times very gradual. Bower regards apogamy and apospory as 
merely a simplification of the life cycle and states that “the 
fact that apogamy and apospory occur on the same plant is a 
coincidence rather than a point of further importance.” 
