1904] = LYON: EVOLUTION OF THE SEX ORGANS 287 
dition of the sex cells the preliminary announcement of apogamy 
in Selaginella rupestris may be made. 
It may be recalled that 
this is the form of Selaginella with a reduced number of func- 
tional megaspores (one or two) which are not shed until the 
embryo is fully equipped with leaves and root. 
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BiG 162 Ay = 
theridium of Atrich- 
um, showing two 
chambers, 
with the sunken sex organs of Lycopodium, 
Botrychium, Phylloglossum, Equisetum, and 
the archegonia of Selaginella, Isoetes, and 
Anthoceros, which have no sterile jacket. 
These, to my mind, represent a different line 
of evolution from the emergent sex organs 
with long necks and stalks. 
_ of the pluriculocular sporangium-like body of a definite form 
In certain locali- 
ties, the microspores are rarely produced and 
the embryos are frequently formed from the 
initial cell of the archegonium. Until the third 
or fourth division of this initial, it is impossible 
to determine whether a normal archegonium 
will result or an embryo. | 
The development of the antheridium of the 
Anthoceros group has until recently been 
looked upon as unique. The male organ of no 
other group is known to arise from a hypo- 
dermal cell. The fact that this antheridium, 
sunken below compact tissue, has a well-devel- 
oped wall, militates against the view that it is 
a primitive form. Emma Lampa (11) has 
noted Anthoceros plants which develop emer- 
gent antheridia arising from superficial cells, 
similar to those of other Le 
groups of liverworts, and 
believes them to bea re- 
version to an ancestral 
form. I do not regard 
them in the same class 
Fic. 15.— Branch- 
ing antheridia of Os- 
munda (? 
Davis’s theory 
and bisexual character, essentially an emergence of fertile tissue 
from the surface of a hypothetical thallus body which came to 
