166 , BOTANICAL GAZETTE (exrnieanl 
already become invisible in this region of the stem, as is seen to be 
the case in the stem represented in fig. 8. These bundles soon become 
quite numerous and run upward for some distance before resuming 
their collateral structure and passing outward to the leaves. 
Two points of interest in this plant are the existence of a well- 
marked internal as well as external phloeoterma in the young stem, 
and the early disappearance of the internal phloeotermal layer. It 
can hardly be doubted that the thin-walled tissue forming the pith 
of the stele is simply extrastelar tissue which enters at the base of 
the stelar system, and through the cotyledonary gap. Absence of 
the protostelic condition is probably to be accounted for by the shape 
of the stem; it is in the region of the cotyledonary gap that the central 
cylinder shows its most primitive condition, namely a vascular tube 
possessing both external and internal phloeoterma. The spaces 
between the vascular segments in the basal region of the stem are 
not foliar gaps, as JEFFREY’s account seems to imply (6, p. 29), for this 
region of the stem is the hypocotyl, and further there are no outgoing 
bundles between the segments referred to. Separation of the seg- 
ments may be due to expansion of the young stem as it assumes its 
tuberous shape. 
CALLA PALUSTRIS has been sufficiently described by JEFFREY (6). | 
The development of its stele follows pretty closely the course out- 
lined for Acorus, though the endodermis does not seem to be well 
developed in Calla, also the foliar gaps extend for a greater distance 
than is the case in Acorus. 
Philodendroideae.—ScuizmatocLorris ROEBELINII seems bi 
show a scattered disposition of the vascular strands in all parts of its 
seedling. The material available has not permitted a satisfactory 
study. 
PELTANDRA VIRGINICA.—The seedling possesses a tuberous base 
consisting of a somewhat cylindrical axial portion with a thick coty- 
ledon applied to its side; the cotyledon is separated in its upper pat 
from the axial portion by a prominent absciss layer. In fig. 9, © 
represents, the-cotyledon, and r, r secondary roots. A section through 
the basalfpart of the tuber shows about eight collateral bundles 
arrangedtin’ a’ circle (fig. 10). Most of these bundles are given ¢ 4 
to the cotyledon, so that only a few slender strands continue the ce | 
