490 OPHIOGLOSSALES 
Bruchmann to the hypobasal hemisphere in O. vulgatum, but to the epi- 
basal by Jeffrey in B. wrginianum, where the whole hypobasal hemisphere 
goes to form the foot. In J. Zunaria Bruchmann found it impossible 
to refer it with any certainty to either. These facts, taken together with 
a similar uncertainty in the embryos of Zguzse¢wm, and the demonstration 
in the Lycopods that the root is variable in its point of origin, show 
that its indeterminate position is a frequent feature in the embryos of 
the strobiloid Pteridophytes, however constant it may ‘appear to be in 
the Ferns. 
Regarded as a whole, the Ophioglossaceous embryos without suspensor 
consist of a simple shoot, of which the polarity becomes apparent relatively 
late, but it is of the same nature as that seen in Jsve¢es, in Egudsetum, 
and in the Ferns. The apex of the axis, arising in close relation to the 
intersection of the epibasal octant walls, is directed to the neck of the 
archegonium: the foot occupies the opposite pole, and the root appears 
as a lateral, accessory part, of indeterminate position, but of relatively 
early origin, and precocious growth. 
The other type of embryogeny seen in B. ob4iguum shows an exactly 
inverted polarity: the condition appears to be comparable to that of the 
Lycopodiales (excl. Jsvetes): the pole directed towards the neck of the 
archegonium becomes the suspensor, while the opposite pole develops 
the embryo, having parts quite comparable in position to those, for 
instance, of Selaginella spinulosa,’ but with an early and strong assertion 
of the first root. The importance of this lies in the relaxation which 
such a fact brings from any rigid view of embryonic development: it 
seems completely to disprove any morphological predestination attaching 
to the primary cleavages of the zygote in the Pteridophytes. 
The materials of this discussion may now be drawn together into a 
general hypothesis of the morphology of the sporophyte, as it is seen in 
the Ophioglossaceae. At the outset it has been concluded that the some- 
what inconstant occurrence of mycorhiza in the sporophyte is not a sufficient 
reason for assuming that the family has undergone general reduction: in 
the absence of any such preconception the family may be treated com- 
paratively as an ascending series, though with the recognition of occasional 
teduction. The facts before us are in accord with the following account 
of it. The embryo sporophyte achieves an early polarity, marked by the 
definition of the stem-apex: the base of the shoot thus initiated is 
represented by the foot, or in 2B. obliguum by the suspensor. The 
primary axis thus defined continues its growth, with rare bifurcation, 
throughout the life of the stock; but adventitious or axillary buds (usually 
arrested) may be formed, which simply repeat the development of the 
primary shoot. The axis bears leaves in spiral or dorsiventral succession, 
and they are all of one primitive type, though liable to differentiation. 
1Compare Bruchmann, 4c., Taf. iii, Fig. 63. 
