190 Lady Isabel Browne. 
glossum is clearly related, and from which it has been suggested 
that it arose by reduction. As the protocorm of Phylloglossum 
is the largest and longest lived of the order, it would be possible to 
consider that it had recently acquired internal phloem, but this 
would not account for the internal phloem of the axis of the cone 
and the pedicel of the young tuber. In these the internal phloem 
can hardly be other than a vestigal character, retained in spite of 
reduction. 
On the whole then, although the evidence is somewhat contra¬ 
dictory, the probability is that the possession of a protocorm is not 
a primitive character of the Lycopodiaceae. It is almost certainly 
not primitive for the Lycopodiales as a whole. 
Turning to the general anatomy we find that Phylloglossum 
differs from Lycopodium in two points ^besides the occasional 
presence of internal phloem already considered. In Phylloglossum 
the xylem of the protocorm and of the axis of the cone is mesarch, 
while in Lycopodium it is exarch. Since we have seen that exarchy 
is characteristic of what appear to be the more primitive members 
of all the Lycopodial orders, the natural conclusion is that the 
mesarchy of Phylloglossum is less primitive than the exarchy of 
Lycopodium. On the other hand it seems very unlikely that a plant 
so small, and possessing so little vascular tissue as Phylloglossum 
should have acquired fresh and centrifugal xylem. This points, as 
did the presence of internal phloem, to the hypothesis that Phyllo¬ 
glossum is reduced from a form less primitive, in this respect than 
Lycopodium. This is, of course, incompatible with the suggestion 
mentioned above, that Phylloglossum arose by reduction from a 
section of the genus Lycopodium. 
The second difference is that the traces of the protophylls are, 
sometimes at least, quite free from the vascular strand running from 
the protocorm to the axis of the strobilus and are attached to the 
root-traces. This peculiarity seems to be unique, and is pre¬ 
sumably a recently acquired character (one possibly correlated 
with reduction of the stem), for ancestral characters tend to 
reappear in allied forms. 
Mr. Jones has recently shown that two principal types prevail in 
the anatomy of the mature stem of Lycopodium, but that the young 
plant in all cases contains a single triarch or tetrarch, solid, exarch 
stele. In the course of development the protoxylem groups increase 
in number by the splitting and shifting of the strands. The phloem 
either differentiates in bands, or in isolated patches breaking up 
