318 BOTANICAL GAZETTE [May 
enough the use of the suspensor or foot-homologue is to push 
the epibasal hemisphere into the center of the prothallium 
where the food-supply will most abundantly and symmetrically 
surround the developing segment. But to explain in any reason- 
able way how this remarkable inversion of the egg originated is 
quite another matter. The archegone in Lycopodium may be 
regarded as occupying a dorsal position on the thallus as in the 
case of Anthoceros, The Lycopodium prothallium, as seen ina 
primitive type like that of Lycopodium cernuum, not modified by 
adaptation to saprophytic nutrition, is comparable with an 
Anthoceros thallus, not only in the origin of the sexual organs 
but in the vegetative tract also. Yet it is inconceivable, | think, 
-how an egg developing after the manner of an Anthoceros 3g 
should invert itself in the archegone, convert its foot into a sus- 
pensor, and develop from its abnormally oriented epibasal 
cell the stem-axis and an adventitious nursing and absorptive 
tract. The inverted position of the Lycopodium egg cannot then 
be regarded as a primitive modification of the Anthoceros com 
ditions. Rather would it appear that between the Antes 
embryogeny and the Lycopodium embryogeny some eT 
had intervened. 
It is possible, though no doubt extremely sp 
refer the inversion of the Lycopodium egg to a doul 
ment, under adaptive conditions, of the archegone 1 ues oe 
tral forms. While the archegone was situated on a vi as 
side of the prothallium the tipping of the embryo _ : ak 
in the ancestors of the Polypodiacez ; following this : a ja 
gone worked back to the upper surface of the pee 
ing the egg in its derived position. As the archegon® . dor 
in successive generations, more and more to the ee ee posi- 
position, the embryo adapted itself to the a ee n hetet- 
tion for nutrition and subsequent development, at abryasie 
ospory originated, the Selaginella type, in which the < 
epibasal tract is immediately thrust into the cen ame into 
spore by the elongation of the primitive foot aan if placed 
existence. Such an epibasal area of the embry® * 
eculative, t© 
ble displace 
nces- 
