352 BOTANICAL GAZETTE [NOVEMBER 
SON 17, IrmiscH 10), in that the protrusion of the petiole base 
carries with it the bud inclosed by the petiole sheath. 
In E. albidum two runners are usual, while the species from the 
western United States and Eurasia normally form but one. The 
length of the runner may be so much reduced as to pass unnoticed, 
but unusual conditions may demonstrate the presence of the 
typical structures not otherwise distinct. When but one runner 
is formed, or when the bulb is renewed in situ, the main stem apex 
is the active structure, the axillary buds if present remaining unde- 
veloped. 
There seems to be a moisture relation on the part of the growing 
runners. Plants of E. americanum growing in well-drained wood 
soil were found in several cases to have few runners; while other 
plants of similar general appearance, but in wet soil at the bottom 
of the same hill,. showed runners in most individuals. It is notice- 
able about Baltimore that those individuals which grow in heavy, 
wet soils produce runners earlier and more abundantly than those 
of drier habitats. The development of abundant runners would 
hasten the attainment of full depth on the part of a particular — 
group of plants, and this would be manifest in the greater frequency 
of flowering plants in a colony of stated size. The conditions under 
which the plants grow are evidently directly related to flower 
production, as the abundance of bloom has been observed to be 
associated with abundance of moisture in each of the habitats 
examined during the work here discussed. 
In moist chamber experiments it was found that the tips of the 
runners were positively geotropic when lying on the top of saturated 
sphagnum, a little free water being present in the dish (fig. 23). 
In the absence of free water in the dish, the response was less 
marked, and in mere dampness it was a negligible quantity. In 
testing to determine whether the downward growth of the tips 
under abundant moisture is due to a moisture response OF bi 
gravitation, experiments were made with moist sphagnum 
different positions in reference to the growing runners. The slow 
growth and the sluggish response on the part of the runners made 
the experiments inconclusive. In the moist chamber a period of 
two or three weeks was needed to carry through a set of tests. 
