35 6 Burt. — The Development of 
hyphae, the sides of the head would be carried farther and 
farther apart, until finally they would become directed obliquely 
downward about the sides of the medullary bundle M. 
N would thus become a dome resting on the top of the bundle 
M , with its sides extending obliquely downward about that 
bundle. Throughout this process the point m of the youngest 
stage would be regarded as close underneath and against the 
closed end of the forming dome, and having in later stages 
the position of the point r in my Fig. 5. The basidia were 
regarded as arising on the lower surface of the dome 
from the portions of N, which were so recurved as to face 
towards M. 
This theory was directly misleading as regards the phylo- 
genetic relationships of the Phalleae. In the Clathreae the 
hymenial tissue is within the receptaculum, and the free ends 
of the basidia face towards the periphery ; in the Phalleae the 
hymenial tissue is on the outside of the receptaculum, and 
the free ends of the basidia face towards the longitudinal axis 
of the plant, as shown in Figs. 5 and 6. In these two respects 
the conditions in the Phalleae are exactly the reverse of 
what they are in the Clathreae. These differences, taken in 
connexion with the course of development that was accepted, 
would be reconciled by an origin of the Phalleae from some 
Anthurus-like member of the Clathreae by a protrusion 
upward — from the upper end of the rudiment of the recepta- 
culum of that ancestor — of the tissue which was to give rise 
to the gelatinous layer of the volva and to the hymenium. 
By spreading out above the receptaculum and then recurving 
downward about it on the outside, the hymenial structure 
would have come to have the position on the outside of the 
receptaculum characteristic of the Phalleae. This would also 
have given the relative inversion in the direction of the basidia. 
The basidia, having a position in the young Clathreae close 
against the inner side of the receptaculum, with their free 
ends directed toward the periphery of the egg, would, upon 
coming outside the receptaculum and recurving downward, 
come to face in the opposite direction, or toward the axis. If 
