Strobilus in A rchegoniate Plants . 359 
upgrowth of papillae, which develop into the pinnae ; more- 
over, the whole of the wing-surfaces is not occupied by the 
eruptive growths, so that the smooth and the eruptive 
conditions may often be seen at different regions of the wings 
of the same foliage-leaf. Again, in certain flowers, as in the 
Hypericaceae and Myrtaceae, the originally smooth surface 
of the staminal growths shows an eruptive development of 
numerous stamens. Thus, whether in the vegetative or floral 
regions, eruptive formation of new parts from a smooth surface 
is known. I have elsewhere contended for a consistent 
morphological treatment of the shoot throughout (Phil. 
Trans. 1884, Part II). Botanists recognize the appearance of 
pinnae by an eruptive process on the margins of the leaf, and 
would, I presume, admit that simple leaves preceded compound 
ones. What I suggest now is that the origin of the sporan- 
giophore or sporophyll in the descent of Vascular Cryptogams 
from some simpler Archegoniate forms was by a similar 
eruptive growth from the smooth surface of a body of the 
nature of a sporogonial head. 
Having thus cleared the ground, and having recognized as 
possible factors in the advance a process of septation by 
formation of sterile septa from a previously continuous arche- 
sporium, and an eruption of the surface so as to produce 
appendicular organs, I will now briefly state certain views 
at which I have arrived as regards the morphology of the 
Pteridophyta, but the detailed production of facts will have 
to be given elsewhere. 
Fixing attention mainly on the spore-producing region, 
since for reasons already noted the sporogenous tissues are to 
be regarded as primary, we see on the one hand among the 
Bryophyta that the spores are produced on sporogonial heads, 
with a central sterile columella, surrounded by a continuous 
archesporial layer, and protected by an external wall. Select- 
ing some small-leaved, strobiloid Vascular Cryptogam, we see 
the strobilus performing the same function of spore-production> 
but with different superficial conformation. Centrally is the 
sterile tissue of the axis, the internal part of which may be 
B b 
