377 
Reply to Criticisms. 
By the term ‘ leaf-segment ’ or c pinna ’ I understand a 
marginal lobe of a leaf, and pinnae are habitually arranged 
along the marginal lines, alternately or in pairs, and show 
a common rule of development. Occasional coalescence of 
pairs of such outgrowths across the adaxial face of the leaf 
are known. But in this case, if the c fertile spikes ’ are pinnae 
or leaf-segments, comparable to those of Aneimia or of 
Osmunda , or the vegetative lobes of Botrychium , there 
must have been a frequent and irregular migration of 
individtial pinnae from the margins to the surface of the 
frond : to such an irregular migration of individual pinnae 
I know no parallel. Quite apart from comparative considera- 
tions as brought forward elsewhere, this difficulty, together 
with the irregularity of distribution of the fertile spikes on 
the leaf, the frequency and irregularity of their branching, and 
the indefinite form of the terminal lobe, dispose me against 
this apparently simple explanation of the frond of Ophioglossum 
palmatum. I shall hope to have the opportunity of examining 
alcohol-material before stating that view of the nature of the 
frond in this species which I have entertained all through this 
work, but not yet stated, because want of alcohol-material 
had made a detailed examination hitherto impossible. 
I wish also to reserve my answer to Professor Goebel's 
objections with regard to Botrychium 1 . I have long been 
aware of the frequent presence of sporangia on the usually 
sterile frond of Botrychium , and have had museum specimens 
showing it in my possession for many years : the fact of their 
presence is certainly a difficulty, which I shall hope to meet 
in the course of a general discussion of the subject. 
The opinion appears to be held by some that the sporan- 
gium cannot undergo such elaboration of form and structure 
as I suggest. It is true that such elaboration has not hitherto 
been demonstrated, but those who are actively engaged in 
morphological inquiry will be disposed to believe all things 
possible, though all may not be convenient. The fact that 
demonstration has not yet been given does not preclude its 
1 loc. cit. p. 359. 
