354 Schively — Contributions to the Life History of 



within a short time — indeed, within the life of the indi- 

 vidual. Doubtless, we may picture the frequent occur- 

 rence of just the proper combination of circumstances ne- 

 cessary to cause a similar transformation of the aerial 

 legume. Consequent upon its production followed the 

 more successful germination of the seed, and certain struc- 

 tural changes were initiated. The characteristics once ac- 

 quired, were slowly, but persistently transmitted, until the 

 habit of the plant as regards subterranean seed-production 

 is now a permanent one. 



It is puzzling to the biologist why in many instances 

 Ampliicarpoza still yields quantities of aerial seed from 

 which, it appears, the species is so little benefited. Varia- 

 tion due to environmental conditions is in Amphicarpcea 

 beautifully illustrated, and in the history of few plants is 

 it possible to obtain a series equally valuable for demonstra- 

 tion of a transitional condition; for the presence of corolla, 

 the number, size and degrees of perfection found in the 

 stamens, the ovary, style and stigma — all afford material 

 which is deserving of careful comparative investigation. 



In conclusion, the facility exhibited by certain of the 

 axillary runners, in acquiring new habits of growth, which 

 are continued through life, deserves emphasis. It has 

 already been stated that in case of injury to the main stem, 

 the cotyledonary axillary shoots and also those from the 

 axils of the simple leaves — themselves non-twiners — will 

 assume the duties of the main shoot. While the latter remains 

 uninjured, or should injury occur after the runners have be- 

 come five or six inches long (perhaps shorter) no amount of 

 artificial assistance and training is sufficient to induce the 

 twining habit. Since the experiments recorded in the early 

 part of this paper were performed, axillary shoots from the 

 simple leaves have been fastened so that they were made to 

 grow upward. Many of these have now reached the height of 

 five feet, and are nearly on a level with the main stem, yet 

 their free ends do not twine. Their actions indicate nega- 

 tively heliotropic and feebly geotropic tendencies. The 



