46 RENNERT: SEEDS AND SEEDLINGS OF ARISAEMA _ 
soon as the hypocotyl has found its way into the ground. Seed- 
lings of A. Dracontium vary greatly also in the number and kinds 
of roots which they send forth. Those with the most well de- 
veloped system have two primary roots from the base of the 
hypocotyl and later a thick root arising adventitiously from the 
the nodes. This secondary root, becomes contractile and trans- 
versely ridged for part of its length. One of the primary roots 
also often becomes contractile and helps to draw the corm deeper 
in the ground. A secondary root, however, is developed only in 
those seedlings which also send up a plumule and a few even of 
these have none. The seedlings in which the plumule has not 
started into activity have as a rule two primary roots, one of which 
becomes thickened and assumes the function of contraction. In 
some cases neither of the primary roots is contractile and in others 
only one short thin root is produced. A direct correlation be- 
tween leaf and root development is here evident. Variations in 
the structure as well as the number of the roots occur. The con- 
tractile roots which are for the most part simple have been ob- 
served occasionally to be branched. In another instance (the at 
single case in which two contractile roots occurred in the lot of 
A. Dracontium seedlings observed) two contractile roots were fused 
for part of their length. The root system of A. #iphyllum is very 
much better developed than is that of A. Dracontinm, for the roots 
are both longer and more numerous. The seedlings have always 
two and often three primary roots which reach a length of 5 cm. 
and in addition after the seedling is well under way, three thick 
adventitious roots appear, budding from the nodes. These roots 
are contractile and show the same transverse ridges as the con- | 
tractile roots of A. Dracontium. In some cases they pull the 
hypocotyl! down as much as 2 or 3 cm. below the level at which it 
germinated. After the secondary roots become firmly established, 
the primary roots grow no more and the greater part of the entire 
root function is discharged by the contractile roots which bear root 
hairs near their tips and become about 7 cm. long. 
The only difference in microscopic structure between the con- 
tractile, secondary and primary roots consists in the greater radial 
elongation of the cells of the inner cortex of the contractile roots. — | 
In A. Dracontium the root stele of the primary root ‘shows a diarch | 
Screech nena 
