50 Sargant. — Theory of the Origin of Monocoty ledons 
On the whole the point to which I attach most importance 
is the gathering-up of the cotyledonary bundles into two 
groups which occurs in four out of the six species I have 
examined with care. Of the three species partially examined 
Euterpe edulis appears to resemble Thrinax , but the whole 
process is obscure. The cotyledonary traces have not been 
followed into the hypocotyl in Geonoma and Chamaevops. 
Thus in four species out of seven there is a twofold 
symmetry in the traces of the cotyledon within the transitional 
region. In two more the symmetry is fourfold. The seventh, 
Phoenix dactylifera , shows an exceptional vascular symmetry 
corresponding with the exceptional habit of the whole seedling. 
Scitamineae. 
Five species from five different genera of this family have 
been worked out by Miss Thomas with success. They fall 
naturally into two groups. 
The species of Musa and Carina are large and generally 
fleshy plants. Their seedlings resemble those of arborescent 
or shrubby genera, and their vascular symmetry corresponds 
to this habit. A number of massive bundles are found in the 
cotyledon. They are continued downwards into the hypocotyl, 
and with the assistance of plumular traces they form a poly- 
arch root-stele. 
The seedlings of Amomum , Elettaria , and Renealmia are 
of a different character, less fleshy, and rather of the herbaceous 
than the shrubby type. The three species examined in detail 
are Amomum angustifolium , Elettaria cardamomum , and 
Renealmia racemosa. Their vascular symmetry is strikingly 
similar. 
The apex of the cotyledon remains permanently in the 
seed. It contains two bundles which there appear equivalent. 
They run the whole length of the petiole and sheath. But in 
the upper part of the sheath they are not symmetrically 
placed with regard to its outline. One occupies the position 
of a midrib, while the other might be taken for a lateral 
bundle without a pendant on the other side. This want of 
