466 OPHIOGLOSSALES 
never large, but appears only as a slight swelling which remains in close 
relation with the prothallus. The root rushes forward in its development, and 
forming its apical cell early (perhaps it is rightly recognised in cell “w” 
in Fig. 260), it attains a considerable length: it bursts freely through the 
prothallus before there is yet any definite trace of the apex of the axis 
or of the cotyledon (Fig. 260 dzs). Up to this time the embryo is stored 
with nutritive substances, but it contains no endophytic fungus. It appears 
that the development up to this stage occupies several vegetative seasons. 
The differentiation of the shoot which is thus long delayed accompanies 
the origin of the second root, which is formed endogenously close to the 
proximal end of the vascular strand of the first. Immediately above this, 
Fic. 260 
Ophioglossum vulgatum, L. The central figure shows an archegonium, at period of 
fertilisation. x225. The left-hand figure shows the first division of the zygote. 225. 
To the right a more adanced embryo. /, /=basal wall; ef=epibasal ; Ay=hypobasal 
hemisphere ;_/=the region of the foot; w=root. 225. (After Bruchmann.) 
and opposite the neck of the archegonium, the cotyledon and the apex 
of the axis appear simultaneously, the cotyledon being on the side of the 
axis next to the first root: surrounding both axis and cotyledon is the 
first sheath (Fig. 260 d7s, h4,). The cotyledon remains quite rudimentary: 
it is followed by a second leaf, which may develop as a small sterile leaf 
expanded above ground, up to which time the embryo has been growing 
some eight to ten years. The third leaf, expanded in the following year, 
may, under favourable circumstances, bear a fertile spike. The further 
development then follows as in the mature plant. 
Campbell, having examined several tropical species, recognises three 
types of embryogeny in the genus, that of O. vulgatum, above described : 
that of O. moluccanum, described by Mettenius and by himself; and that 
of O. pendulum, on which he has added largely to the observations of 
Lang, and finds that the embryo is variable within the species. According 
to his statement, the first type is characterised (as we have seen) by an 
