358 Bower. — A Theory of the 
elsewhere (Phil. Trans. 1894), and those relating to the 
Ophioglossaceae are nearly mature ; in both cases the develop- 
mental facts support a view of septation. It appears to me 
that morphologists have in the past been too ready to take 
refuge in hypotheses of reduction, as applied to the homo- 
sporous Archegoniatae. It has been assumed, with, as 
I think, too little reference to the biological position of the 
organisms, that synangia were the result of coalescence of 
originally distinct sporangia. I hold that, on considerations 
of development, comparison, and biological position, there is 
good reason to believe that certain at least of the plants 
bearing synangia were on the up-grade of evolution, and that 
septation has been a factor in producing them as we now see 
them. 
There is one further factor which it will be necessary to 
discuss, as contributing to the advance of the sporophyte from 
similar beginnings, viz. the origin of appendicular parts. The 
origin of the root may be dismissed as not directly affecting 
our present discussion, and there will remain the question of 
origin of such parts as are included under the terms sporan- 
giophore, sporophyll, and foliage-leaf. It is conceivable that 
there may have been various modes of origin of such parts, 
and that they are not all truly comparable as regards their 
descent ; but I think there is good reason to believe that at 
least one mode of origin was by a process of eruption from 
a hitherto smooth surface. This suggestion is in no way 
subversive, but falls in with observed facts of the origin and 
development of leaves in vascular plants generally ; whether 
we take the strobilus or the vegetative shoot, the ontogenetic 
origin of the appendicular parts might be described as eruptive. 
What I suggest is, that the phylogenetic history of sporophylls 
was similar to the history of the individual as we now see it. 
It is easy to bring forward examples of analogous eruption 
of new parts of a higher order from the smooth surfaces of 
other parts ; for instance, in the development of simple foliage- 
leaves the margins are occupied by smooth wings; in com- 
pound leaves, however, these smooth surfaces show an eruptive 
