3 j6 Seward . — The Anatomy of Lepidodendr on aculeatum , Sternb. 
the outer edge of the wood and the inner cortex has suffered considerably, 
either from disorganization of the tissues before petrification, or perhaps to 
a large extent from the effects of secondary crystallization. In the portion 
shown in Text-fig. 2, the preservation is exceptionally good ; the xylem 
is succeeded externally by a broad band of small-celled parenchyma (m) 
which is darker and denser along its inner margin. This is the tissue 
which previously has been described as the meristematic zone 1 ; it is com- 
posed exclusively of short parenchymatous cells, and in other examples of 
Lepidodendron it is known to be the seat of secondary growth. In the 
portion of this zone seen in Text-fig. 2, there are no indications of meri- 
stematic activity, but a few radially elongated cells occur in other parts 
of the same section which are identical in form with the elements figured in 
some of the specimens of L . fuliginosum from the Binney Collection. 
The leaf-traces follow an almost vertical course in the meristematic 
zone, and they pass through the cor- 
tical region at an unusually small angle 
(Text-fig. 3 , It). The xylem-strand as 
seen at It, in Text-fig. 2, is approxi- 
mately circular in outline with the 
smallest tracheids in a more or less 
central position. The broad paren- 
chymatous zone m is succeeded by 
a slightly narrower band composed 
of large clear spaces interspersed with 
very dark lines and patches of dis- 
organized smaller cells. This tissue is 
preserved in a few patches only, but it is sufficiently distinct in the portion 
represented in Text-fig. 2 , .y to demonstrate its identity with the tissue 
which I formerly described as the secretory zone 2 , but which Professor 
Weiss 3 prefers to designate phloem. The nature of this tissue has been 
described in previous accounts of lepidodendroid stems, and reasons have 
been brought forward against my objection to recognize it as phloem. 
A recent examination of several sections of Lepidodendron fuliginosum , 
which Professor Weiss generously sent to me from the Manchester Museum 
Collection, does not lead me to modify views already expressed. The 
tissue in question does not exhibit such histological characters as seem 
to me to justify the title of phloem, as understood in the case of recent 
plants. 
A band of compact parenchyma composed of small and rather dark 
elements abuts on the secretory zone ; this is the inner cortex (Text- 
fig. 3 , c), and it appears to be identical in structure with the corresponding 
region in other lepidodendroid stems. The boundary between the inner 
1 Seward (’99), (’02). 2 Seward, loc. cit. 3 Weiss (’01), (’03). 
Fig. 3. 
