5 1 4 Boodle . — Comparative A natomy of the 
(1) If we accept the evidence derived from the seedling 
as thoroughly reliable, the absence of internal phloem in it 
proves that Osmunda has not been derived from an amphi- 
phloic siphonostelic form, and that the local occurrence of 
internal phloem in the mature stem has been entirely misin- 
terpreted by Faull and Jeffrey. 
(2) If, on the other hand, one accepts their interpretation 
of the internal phloem, occasionally present in the mature 
stem, as a primitive structure, then the absence of a stage 
in the seedling showing similar structure proves that the 
ontogeny is not reliable as an index of structural phylogeny. 
This would strike at the root of Jeffrey’s whole generalization 
(which is chiefly founded on ontogeny) as to amphiphloic 
siphonostely being the type of structure which succeeded 
protostely in Ferns, and gave place in certain cases to medul- 
lated monostely by reduction 1 . For if the seedling-stem is 
at all dependable in repeating the structural history of the 
mature stem, one might of necessity count on Osmunda 
cinnamomea to show clear ontogenetic evidence of the previous 
existence of internal phloem, as, on our present assumption, 
it is a plant so little removed from the solenostelic condition 
that certain individuals of the species actually produce, by 
reversion in their mature stems, well differentiated local 
solenostelic structure. Thus it appears that either the basis 
of Jeffrey’s theory, referred to above, is unsound, or the 
structure of Osmunda does not bear out Jeffrey’s interpreta- 
tion of it, and this genus forms an exception to his genera- 
lization. 
The disagreement between Jeffrey’s deductions from the 
anatomy of the mature plant and the evidence derived from 
the seedling, has already been pointed out by Scott (’02, 
p. 209) in a review. 
The case of Osmunda has been referred to thus fully, 
because evidence of a similar nature has to be dealt with 
below in the case of Schizaea. 
1 There is certainly no sufficient evidence for regarding an inner endodermis as 
proving, in cases where it occurs, the previous existence of internal phloem. 
