364 
Bower. — A Theory of the 
Moss-sporogonia has been held. The result of this would be 
that the apex of the sporophyll would compare with the apex 
of a sporogonium, or of some branch of it. In suggesting that 
the whole strobilus is the equivalent of some body of the nature 
of a sporogonial head, clearly the apex of the one will correspond 
to the apex of the other, while the eruptive members will be 
mostly or all lateral. 
In entertaining this theory, we shall necessarily part company 
with the old views of metamorphosis, and I must state, with all 
distinctness, that the opinion that the strobilus is a result of 
modification of a vegetative shoot is, to my mind, incompatible 
with our present views as to descent of plants constantly 
maintaining an antithetic alternation, in which spore-production 
was a regularly recurring event. On grounds of comparison 
the converse would appear to be more probable ; but in any 
case there seems no sufficient reason to think that the strobilus, 
or indeed the Phanerogamic flower, ever was a foliage-shoot. 
In conclusion, I would not be understood to take up a dog- 
matic attitude as regards any of these questions. While 
recognizing septation as one mode of origin of separate 
sporangia, I would not deny that other modes may have 
occurred. Similarly, while tracing the origin of some vegetative 
leaves to the sterilization of sporophylls, I do not deny other 
sources of origin of foliage-leaves. Nor do I put forward this 
theory of the strobilus except in the most tentative way. The 
stability of a theory is to be measured by the extent of the 
facts which it will satisfactorily cover. I think those who 
carefully consider the matter will find that a very large number 
of facts will be susceptible of more ready interpretation in 
accordance with it. I submit the suggestion as a working 
hypothesis which has been before my mind during some years 
of active investigation. 
The main points of the theory may be briefly stated as 
follows : — 
1. Spore-production was the first office of the sporophyte, 
and the spore-phase has constantly recurred throughout the 
descent of the Archegoniatae ; the spore-bearing tissues are to 
