founded on the Structure of their Seedlings. 41 
remarkable both in external form and in their vascular sym- 
metry. I shall describe the latter at some length, as it offers 
points of interest, though I believe it to be in all probability 
derived from some form resembling Agave rather than of 
more primitive character. 
Alstroemeria (garden variety). The cotyledon remains in 
the seed as a sucking organ. It contains two bundles which, 
though distinct from each other down to the middle of the 
sheath, are close together, and occupy the position of a midrib. 
Just above the entrance of the plumular traces into the stele, 
the two cotyledonary traces approach each other, and their 
protoxylem groups unite. They now form a double bundle 
resembling that of Allium (PI. V, Figs. 1 and 2). The plumular 
bundles unite to form two massive traces, and these enter the 
hypocotyl at the same time with the double trace from the 
cotyledon. The transition to a diarch root-stele takes place 
exactly as in Arthropodium (p. 30), but the stele subsequently 
becomes tetrarch. This takes place by the formation of new 
protoxylem groups (cf. Fritillaria alpina> p. 25) ; not as in 
Chlorogalmn by the survival of two which were at first sup- 
pressed. 
Bravoa gemmiflora. The cotyledon remains within the 
seed as a sucking organ. It contains four bundles in the 
sheath, all quite distinct from each other. Two, distinguished 
from the others by their size and position, represent the main 
bundles. These two approach each other in the transitional 
region without uniting. The plumular traces insert themselves 
on those from the cotyledon, and the root-stele is triarch. Its 
formation seems to be governed by cotyledonary traces only. 
Agave spicata. The whole seedling is succulent. The 
cotyledon, after sucking out the food from the endosperm, 
emerges from the ground as a green fleshy spike of 
triangular section, carrying the seed-coats on its apex. It 
contains four bundles, of which two, from their size and 
position, can be identified as the main bundles. There is 
a comparatively long hypocotyl in these seedlings, with a stele 
