Danaea and other Marattiaceae. 
539 
necessary material it could not be decided. There is nothing 
peculiar about the meristeles themselves in this region. They 
are comparatively small and anastomose at not very frequent 
intervals. Figs, n and 12, PI. XXII, are from the primary 
axis ; Fig. 13 is just below the first pair of pinnae ; Figs. 15- 
17 represent the pulvinus and rachis of one of these pinnae, 
and Fig. 14 the pulvinus of the other. In the last named 
there is a gamomeristelic ring, which in its structure recalls 
the solenostelic stage of the Danaea-seedling, or the soleno- 
stele of Marsilia . In the leaf, however, there is no external 
nor internal endodermis. The absence of mucilage canals in 
Figs. 14 and 15 shows that these structures are not continuous 
from the primary to the secondary and succeeding axes. 
As is well known, the collenchyma of the pulvinus passes 
into the pale yellowish (sometimes even faintly brownish) 
sclerenchyma of the rest of the petiole and the rachis 1 . 
In the leaf the mucilage-canals do not seem to have any 
very definite arrangement. They generally pursue a fairly 
continuous longitudinal course, sometimes branching and 
forming an occasional horizontal anastomosis. They some- 
times also end blindly. Tannin-sacs are abundant and are 
usually arranged round the meristeles. The black dots in 
Figs. 12, 13, 15, 16, 17 represent the tannin-sacs. 
One of the chief objects of the investigation was to ascertain 
if there were any anatomical features which by their form, 
position, variation in presence or absence, afforded means of 
generic or specific distinction. It has already been pointed 
out that the arrangement of the petiolar meristeles of the 
older fronds of Angiopteris distinguishes it from the other 
genera. In addition it was found that to a certain extent 
(1) the sclerenchyma, (2) the mucilage-canals, and, in a less 
degree, (3) the tannin sacs yielded means of anatomical, 
specific or generic distinction. 
1 It may be as well here to again emphasize the fact that the sclerenchyma in 
Danaea is of the usual Marattiaceous type, and not brown like that of the 
leptosporangiate Ferns. This was verified in the fronds of three different species, 
and the rhizome and roots of Danaea alata. Cf. Kuhn, Ueber den anatomischen 
Bau von Danaea , Flora, 1890. 
