Lycopodiales. 189 
In discussing the phylogeny of the protocorm too little attention 
has been paid to the anatomy of Phylloglossum, though M. Bertrand 
published an excellent account of it as long ago as 1885 (3). Dr. 
Campbell, in the last edition of his “Mosses and Ferns” states that 
the anatomy of the vegetative organs, examined by Bertrand, 
corresponds closely to that of Lycopodium, but that the tissues are 
simpler (10). Professor Bovver in his recent “Origin of a Land 
Flora ” discusses the nature of the protocorm, but makes no 
mention of the peculiarity of the vascular tissue of Phylloglossum, 
though the structure of the stele has an important bearing on the 
primitiveness of the genus and therefore of the protocorm (7). 
The protocorm or tuber of Phyllogossum, which appears to re¬ 
place the stem, bears protophylls and roots, and in exceptionally 
vigorous plants its apex grows out into an axis terminated by a 
cone. According to M. Bertrand’s account the lower part of the 
protocorm contains no vascular tissue; vascular tissue is first 
developed just above the insertion of roots and just below the 
insertion of the leaves; it consists of an anterior and a posterior 
mass of xylem embedded in phloem. The peduncle of the strobilus 
also shows, throughout most of its course, internal and external 
phloem ; here, in typical cases, we have the type of structure which 
has since been called solenostelic. The structure of the peduncle 
varies considerably, and, in places, the xylem forms a solid proto- 
stelic mass, or the centre of the xylem may be occupied by a few 
phloem elements. The pedicel, arising from the protocorm and 
bearing the tuber of the next year’s growth, is also, in parts, pro¬ 
vided with internal phloem ; it is probably best regarded as a modified 
cauline portion. What is important for the present discussion is 
that the presence of internal phloem in several parts of Phylloglossum 
renders it almost impossible to regard the vascular tissues of the 
latter as equally primitive with the protostelic species of Lycopodium, 
Selaginella or Lepidodendron. Internal phloem is not found in any 
of the more primitive Lycopodiales ; indeed, outside Phylloglossum 
it is so far only known in Selaginella laevigata, var Lyallii, where, 
as shown above, it is probably a recent modification. On the other 
hand it does not seem conceivable that so small a plant as Phyllo¬ 
glossum should have acquired internal phloem ; therefore it would 
seem that this genus owes its present simplicity to reduction rather 
than to the retention of primitive characters. But on this view it 
is surprising that no traces of internal phloem have been found in 
the protocorm-bearing species of Lycopodium, to which Phyllo- 
