190} BLODGETT—BULBS OF ERYTHRONIUM 369: 
present forms. The species are found to vary from the type found 
in the assumed original habitat approximately in proportion to the 
distance of migration. The species of Eurasia combines features 
of the two groups in its vegetative characters. 
The roots radiate from a point near the base of the bulb, but 
show no definite response to gravity; they maintain a definite 
space relation to each other, defining the surface of a cone in the 
soil, the axis of which is about 45° to the vertical. In development, 
the roots arise in September from cells just below the vascular 
base of the bulb, and grow in straight lines during their elongation. 
In penetrating the bulb tissue, the cells are apparently dissolved. 
by the root tissue, making a cavity about the advancing root 
rudiments. The number of roots increases with the age of the 
bulb. : 
Conclusions 
From the foregoing study the following conclusions may be . 
drawn: The delayed development of the embryo is associated with 
a large store of endosperm; this is drawn upon by the germinating 
embryo during the season when vegetative activity is low; the 
young seedling is established in the soil early in the spring, the 
endosperm furnishing the needed materials for its development. 
With the exhaustion of the reserve material of the seed, the primary: 
Toot is developed, and the cotyledon is elevated into the air and 
light; the cotyledon is the only leaf exposed to the light by the 
Seedling. The stem apex, located in a narrow cavity in the base 
of the cotyledon, is carried forward by the elongation of the embryo, 
and, after the elevation of the cotyledon, is carried farther into the 
soil by the elongation of the walls of the cavity. The short period 
of vegetative activity, and the prompt descent of the stem apex in 
the dropper, would indicate adjustment to short growing seasons; 
the brevity of the active season is a feature of the life cycle. The 
tendency on the part of the seedling to bury the stem apex deeply 
'S continued by the immature plants in the production of runners; » 
™ some cases these are strictly comparable to the dropper of the. 
seedling in structure, in others they involve new developments; but 
the result is the same in either case. 
The persistence of the original stem apex until the establish- 
