35 
Anatomy of the Opkioglossaceae . 
open for a new arrangement of the primary polarity of the embryo which 
may be more satisfactory. A similar rearrangement of polarity is found in 
the Leptosporangiate Ferns where a suspensor is wanting and the initial 
polarity of the embryo is different. 
Thus, while accepting fully Bower’s conclusions as to the importance of 
the primary polarity of the embryo, and as to the probability of the type 
of embryo with a suspensor being relatively primitive, it does not seem to 
me clear, from a consideration of the Marattiaceae and Ophioglossaceae, 
that the suspensor is to be explained as having originated on account of its 
biological advantage, and it is also not clear that the curvature of the 
embryo entails any effective biological disadvantage. I am inclined to think 
that the presence of a suspensor and also the simplification of the embryo 
by the omission of a suspensor may be better explained on morphological 
than on biological lines. 
The alternative view, to which I incline, may be briefly stated. The 
presence of a suspensor of one or two tiers appears to be a fact of organiza- 
tion in a number of forms which are relatively primitive. Its presence may 
be looked upon as the last indication of the construction of the plant body 
from a filament or row of cells, i. e. as a juvenile stage in the development 
rapidly passed over and often suppressed. This juvenile stage may have 
suited the conditions of development and been retained and elaborated, as 
appears to have been the case in the line of descent leading to the Sperma- 
phyta. On the other hand, the non-development of the suspensor may 
have allowed of useful changes in the primary orientation of the embryo, 
but its morphological significance appears to lie in the suppression of the 
last indication of the juvenile filamentous stage. 
I do not propose to enter fully at present into the extended application 
of this way of regarding the suspensor. It may be pointed out, however, 
that it can be supported by analogies from the germination of spores of 
Algae, Bryophyta, and Pteridophyta, where a filamentous stage is often 
hurried over or suppressed. It also allows of application to the somewhat 
similar case of the presence of a cell taking no part in the further develop- 
ment, at the base of the sporogonium of the J ungermanniaceae, and its 
absence in the more direct development of the sporogonium of other 
Hepaticae. 
One other feature of the construction of the embryo in the Filicales 
may be referred to in conclusion. This is the position of the primary or 
first root. Regarding this, Bower remarks : £ It is notable that though the 
root in Seed-Plants directly faces the suspensor, this is not the case in any 
Pteridophyte ; in them it is always a lateral appendage, however nearly 
it may sometimes approach the centre of the hypobasal hemisphere. 
Accordingly it cannot be held to be itself the continuation of the primi- 
tive axis.’ I do not propose to enter into the question as to how far this 
D 1 
