1910] BLODGETT—BULBS OF ERYTHRONIUM 367 
Summary , 
The points presented in this paper may be summarized as 
follows: 
The undifferentiated embryo begins to elongate in the fall and 
organizes a rudimentary stem apex in a narrow cavity at the base 
of the cotyledon. In germination the radicle is thrust into the 
soil during the winter, the stem apex following immediately behind 
the base of the radicle, in the cavity mentioned. The hypocotyl 
is represented by the fusion region between the vascular supply to 
the stem apex and the main vascular system of the seedling; it 
takes no part in the development of the seedling. After absorbing 
the endosperm, the cotyledon is elevated into the air, and acts 
as the first photosynthetic organ. Either two or three vascular 
bundles are present, varying with the species. 
During the activity of the cotyledon as a leaf, the cavity in the 
base of the cotyledon about the stem apex elongates to form a 
slender sheath, with the stem apex inclosed as a termina] bud at 
€ tip. The “dropper” so formed is positively geotropic in 
Fesponse, as is the primary root; the runners and roots of later 
Stages are not positively geotropic. At the close of the season 
the terminal bud of the dropper is isolated in the soil by the wither- 
Ing of other parts of the plant. 
During the summer the first foliage leaf is organized by the 
stem apex and becomes functional the following spring. Roots are 
Protruded at the base of the bulb in the fall, which marks the begin- 
Ning of the second vegetative period. This sequence of develop- 
_ Ment is repeated in the subsequent seasons to the mature bulbs. 
The stem apex becomes inclosed by the base of the foliage leaf, 
and there forms a bud from which the next bulb will develop. 
When the bulb is renewed in situ, only this bud develops; this 
IS also the rule in the species producing but one runner. In E. 
americanum two buds are usually formed in addition to the main 
bud, each of which elongates as a runner and forms a bulb. These 
additional runners spring from buds axillary to the leaf, or to a 
b scale. When but one runner is developed normally by a 
Species, it is formed from the elongation of the base of the petiole, 
Which carries the bulb rudiment into the soil as a terminal bud, 
