[Read before the Texas Academy of Science , December 28, 1898.] 
NOTE ON THE DESCENT OF ERYTHRONIUM BULBS 
INTO THE SOIL. 
0. C. Chaulton, Baylor University. 
It is a familiar fact that tubers, rhizomes and bulbs are generally deeper 
in the soil in age than at the time of beginning their growth. It has been 
determined that these downward movements are caused (1) by a down- 
ward growth of the stem, or (2) by a shortening of the roots with a con- 
sequent pulling down of the stem, or by the action of both these causes in 
the same plant.* 
Some of the conclusions which for some time have been established 
regarding the descent of' various forms of subterranean stems may be 
briefly described as follows: 
1. Plants gradually penetrate downwards by means of root contraction, 
but this contraction diminishes and at length ceases. 
2. Plants may have strongly, weakly, or not at all contractile roots, 
either when mature or immature. 
3. The same plant forms strongly contractile roots when at a shallow 
depth, but weakly contractile roots at a great depth. 
4. In normal cases, roots are strongly contractile in youth, less so or 
not at all in age. 
5. The plant tries to adapt itself by ceasing root contractility if put 
down deep prematurely, but by renewed contractility if its depth in the 
soil is rendered too shallow by removal of surface layers of soil. 
6. Each species has its own maximum depth. 
The phenomena which I here report are only a confirmation of some 
of these conclusions as seen in the Erythronium albidum, or White Dog- 
Tooth Violet. This well-known bulbous plant grows abundantly in cer- 
*In the case of some bulbs the development of new bulbs beneath the old ones 
has been regarded as accounting in part for the deep position of the bulbs. 
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