founded on the Structure of their Seedlings. 25 
ence of the primary root and its physiological activity which 
renders a considerable girth necessary. 
The two cotyledonary traces of the slighter seedling of 
Fritillaria alpina form a diarch root-stele in much the same 
way. It afterwards becomes tetrarch by branching of the 
phloem and division of the protoxylem, and the whole 
transition recalls that of Ornithogalum exscapum. This 
resemblance is probably accidental. 
Tidipa praecox and Tidipa sp. (from Calcutta). 
Two bundles run the whole length of the cotyledon and 
possess a common protoxylem group. They are orientated 
in the way characteristic of double bundles (A, Diagram V). 
A B 
Two plumular traces are inserted on the cotyledonary traces, 
as in Fritillaria (B, Diagram V). A diarch root-stele is formed 
from the cotyledonary traces : the phloem groups are con- 
tinued straight down into the root, while the single protoxylem 
group branches to form a second on the opposite side of the 
xylem plate (Diagram V). In both species the protoxylem 
groups of the root are somewhat extended tangentially, and 
the whole xylem plate is shaped like a dumb-bell. The root- 
stele, however, remains diarch. 
In the three species of Lilium which I have examined 
( Lilium sp ., L. Henryi , L. croceum ), the double trace of the 
cotyledon is even more reduced than in Tulipa ) but the 
transition takes place in precisely the same way. 
Erythronium Hartwegi is the only species I have examined 
from this tribe which does not follow in essentials the method 
