354 PROCEEDINGS OF THE ACADEMY OF [June, 



CONTRIBUTIONS TO THE LIFE-HISTORY OF PLANTS. No. XV. 



BY THOMAS MEEHAN. 

 THE BENDING OF MATURE WOOD IN TREES. 



At the meeting of the American Association for the Advance- 

 ment of Science held in Philadelphia in 1884, Prof. Charles E. 

 Bessey exhibited a drawing of the trunk of a Balsam Fir that had 

 blown over and had bent in such a manner that the curvature could 

 only have occurred after the trunk had become several years old. 

 The prevalent impression is that trees and branches grow into their 

 various forms; or, as the popular phrase expresses it, " as the twig 

 is bent the tree's inclined." No one was prepared to believe that 

 the tree, once inclined, could at any time thereafter change its 

 form. There was nothing in the text-books to indicate the possi- 

 bility of such phenomena. Prof. Bessey 's specimen was looked 

 upon as interesting and curious, but it has had no influence in 

 our text-book teachings. Up to the present time we are taught 

 to look to light, gravitation, tension, turgescence, or some one or 

 another of the surrounding conditions to account for the direc- 

 tion which stems or branches assume the independent energy 

 developed from plant life itself receiving but slight recognition, 

 probably because its exact nature is so far incomprehensible. 

 Prof. Bessey' s experience seemed to throw more light on some 

 of my own observations. In the Proceedings of the Academy 

 of Natural Sciences of Philadelphia for 1866, p. 401, appears 

 my paper " On the Consumption of Force by Plants in Over 

 coming Gravitation, " in which is clearly shown that life-energy, 

 sustained by nutrition, was an enormous power in the life- 

 history of the plant. I was encouraged to make actual experi- 

 ments and wide observations, that have extended from that time 

 till now, only to find the surprising fact that the recurving and 

 incurving of mature growth is among the commonest of phenomena 

 in the vegetable world. Before proceeding to prepare this paper, 

 I inquired of Prof. Bessey if he had investigated the matter fur- 

 ther, and received the following interesting letter: 



