44 RENNERT: SEEDS AND SEEDLINGS OF ARISAEMA 
axis of the embryo. The cells of the parenchyma have also taken 
on anelongated form. The only region in the cotyledon where 
new cells are added is that occupied by the procambium and fibro- 
vascular bundles. Here the cell division is very active. Radial 
growth takes place only as the contents of the endosperm cells is 
absorbed. The shape, arrangement of cells and manner of elon- 
gating are exactly similar in the cotyledons of A. Dracontium and 
A. triphyllum. Jt is only in the fibrovascular system that any dif- 
ference between them has been discovered. Here in both cases, 
as in the procambium strands in the embryo, the bundles near the 
tip, branch and anastomose so that their distribution is irregular. 
At the base, however, the number of bundles is constant. A. Dra- 
contium as a rule possesses six bundles: one of these strands is very 
weak and occupies the same position as the sixth procambium strand 
in the cotyledon, 2. ¢., at the right of the largest central bundle. The _ 
left hand strand which corresponds to the seventh in the resting 
embryo disappears before the cotyledon has proceeded very far 
with its development. The cotyledon of A. ¢riphyllum has five 
bundles arranged as in the resting embryo. Ina few instances ei 
chlorophyl has been found in that part of the cotyledon of A. 
Dracontium which protrudes from the seed both when the plumule 
was functional and when it was not. These cases, however, are 
uncommon. { 
Up to this point there is almost absolute identity in the germi- 
nation of these two species: the only difference between them lies 
in the various sizes which the cotyledons attain. After this stage 
in the germination has been reached, however, various differences 
in the order of development of the organs become apparent. 
The rudiments of all the structures of the mature corm are 
present in the hypocotyl of both A. “iphyllum and A. Dracontium 
and the formation of the corm is brought about by the enlarge- 
ment of the base of the hypocotyl and the laying down in it of the 
definitive tissues. In both it increases in bulk at least to a small 
extent before the first primary root is sent out. The hypocotol 
of A. Dracontium enlarges at a very much more rapid rate in the _ 
first stages of germination than does A. triphyllum and generally _ 
attains a considerable development before the root appears. A 
seedling of 4. Dracontium with two roots each only 1 mm. in length 
