Reply to Criticisms . 375 
experiments, as also with the intercalation of a vegetative 
phase between the zygote and the production of spores. 
But, for my own part, I should be diffident in making any 
general statement on the point of priority of the sporophyll or 
of the foliage-leaf from the point of view of descent, as applicable 
for all Vascular Plants ; and it is not my present purpose to 
discuss this question at large. I desire now only to make it 
clear that there is an unproved assumption involved in the 
passage quoted from Professor Goebel’s paper (p. 359), an 
assumption which, in the absence of proof to support it, appears 
to me to materially impair the validity of his argument. 
If, however, it be contemplated as possible that, in certain 
cases, the foliage-leaf may be, in point of view of descent, 
a sterilized sporophyll, this would greatly alter the face of the 
discussion. I have already intimated 1 that in the Lycopods 
there is reason to believe that a sterilization of sporophylls has 
taken place, and that the result is to be seen in the foliage- 
leaves, which in most species differ from them in little beyond 
the absence (partial or complete) of the sporangium. To me, 
whether we take such simple cases as the Lycopods or the 
more complex case of the Filicineae, the sporangium is not 
a gift showered by a bountiful providence upon pre-existent 
foliage-leaves : the sporangium, like other parts, must be looked 
upon from the point of view of descent : its production in the 
individual or in the race may be deferred, owing to the inter- 
calation of a vegetative phase, as above explained ; while, in 
certain cases at least, we probably see in the foliage-leaves the 
result of sterilization of sporophylls. If this be so, much may 
then be said in favour of the view that the appearance of 
sporangia upon the later-formed leaves of the individual is 
a reversion to a more ancient type rather than a metamorphosis 
of a progressive order. 
The acceptance of such views as those thus briefly sketched 
would materially alter the face of the discussion. While 
recognizing the fact of correlation as demonstrated by Goebel, 
and illustrated more or less clearly in so many spore-bearing 
1 Roy. Soc. Proc. vol. 1 . p. 270. 
