188 Lady Isabel Browne. 
of the root on the swelling seen in this specimen of L. Phlegmaria 
does not correspond to the position of a root on a true protocorm 
(6). But even if this swelling were a true protocorm it would not 
prove the primitiveness of the latter, though it would weigh on that 
side of the question. Again, if the protocorm were primitive, we 
should expect that it would be at least equally well developed in the 
Palaeozoic and Mesozoic ancestors of the Lycopodiaceae as in 
Phylloglossum, where it is quite bulky enough to be fossilized. No 
trace of a protocorm has been found in connection or associated 
with Palaeozoic or Mesozoic Lycopodites. But a stronger argument 
against the primitiveness of the protocorm is that if we regard it as 
the forerunner of the leafy stem we cannot avoid supposing that it 
was found in the common ancestor of the phylum, unless we make 
the unwarrantable assumption that the stem of Lycopodium, the 
anatomy and histology of which are essentially similar to those of 
other primitive Lycopodiales, had a different origin from the stem of 
other Lycopods. But the protocorm only occurs in the Lycopo¬ 
diaceae, where it is associated with late and comparatively small 
development of the vascular tissues. It is very difficult to imagine 
that certain Lycopodiaceae have retained up to the present day an 
organ, the forerunner of the leafy stem, which had in certain members 
of the phylum, in the Lepidodendraceae, been replaced by stems 
that had already attained dendroid proportions in the Devonian age. 
Another of Professor Bower’s arguments against the primitiveness 
of the protocorm rests on the want of sharp differentiation between 
the protophylls or leaves borne by the protocorm and the ordinary 
vegetative leaves. He says that even in Phylloglossum, where the 
distinction between the two is usually more marked, intermediate 
forms between protophyll and sporophyll have been seen (6). The 
latter part of this statement is in direct contradiction to an observation 
of Professor Thomas, who denies the existence, in his specimens, of 
transitions between sporophylis and protophylls (22). It is fair to 
add that in a former paper Professor Bo wer laid great stress on the 
absence of forms truly intermediate between sporophylis and proto¬ 
phylls in Phylloglossum (5). But even if we accept Professor Thomas’ 
statement of the sharp differentiation between protophylls and 
sporophylis of Phylloglossum we must admit that in Lycopodium 
ceruuum the protophylls merge gradually into the foliage leaves. 
The absence or feeble indication of any transition from the proto¬ 
phylls to the other appendages in Phylloglossum would agree with 
Professor Bower’s suggestion that this genus, with its large proto¬ 
corm, may well be the extreme type of a specialized line. 
