138 THEORY OF THE STROBILUS 
place to the axis in the initial differentiation of the shoot. Perhaps the 
most explicit statement on this point is that by Alexander Braun, who 
remarks in his Rejuvenescence in Nature (English edition, p. 107), 
referring to phytonic theories, that ‘all these attempts to compose the 
plant of leaves are wrecked upon the fact of the existence of the stem as 
an original, independent and connected structure, the more or less distinct 
articulation of which certainly depends upon the leaf-formation, but the 
first formation’ of which precedes that of the leaves.” Unger also, in his 
botanical letters to a friend (No. VIII.), described how ‘“ The first endeavour 
.is directed towards the building up with cell-elements of an axis”—“ those 
variously formed supplementary organs which are termed leaves originate 
laterally upon it” and he concludes that “‘we may [therefore] say with 
perfect justice that the plant . . . is, as regards form, essentially a system 
of axes.” Naegeli contemplated a somewhat similar origin of the leafy 
shoot as an alternative possibility ; in fact, that the apex of a sporogonium- 
like body elongated directly into that of the leafy stem, in which case 
the axis would be the persistent and prominent part, and the leaves be 
from the first subsidiary, and lateral appendages. In my theory of the 
strobilus in Archegoniate Plants the central, idea was somewhat similar 
to this.) It may be briefly stated thus: There seems good reason to hold 
that a body of radial construction, having distinction of apex and base, 
and localised apical growth as its leading characters, existed prior to the 
development of lateral appendages in the sporophyte; the prior existence 
of the axis and lateral origin of the appendages upon it are general for 
normal leafy shoots. The view thus put forward is, indeed, the mere 
reading of the story of the evolution of leaves in terms of their normal 
individual development. 
It is natural to look to the Pteridophytes for guidance as to the origin 
of foliar development in the Sporophyte, for they are undoubtedly the most 
primitive plants with leafy shoots. They may be disposed according 
to the prevalent size of their leaves in a series, leading from microphyllous 
to megaphyllous types. I have lately shown that such a seriation is not 
according to one feature only, but that certain other characters which 
have been summarised as “‘Filicineous” tend to follow with the increasing 
prominence of the leaf? This indicates that such seriation is a natural 
arrangement. Now it is possible to hold either that the large-leaved 
Fern:like plants were the more primitive, and the smaller-leaved, derivatives 
from them by reduction; or, conversely, that the smaller-leaved were the 
more primitive, and the larger-leaved derivatives from them by -leaf- 
enlargement; other alternative opinions are also possible, such as that 
the leaf-origin has been divergent from some middle type, or that the 
leaves of Vascular Plants may have been of polyphyletic origin. For the 
moment we shall leave these latter alternatives aside. 
Much of the difference of view as to foliar origin centres round the 
1 Annals of Botany, vol. viii., p. 343. 2 Studies, v., p. 254. 
