202 PROCEEDINGS OF THE ACADEMY OF [1897. 



SOME NEGLECTED STUDIES. 



Botanical pleasures need not end with the first frost. Buds and 

 branches furnish an endless variation, and are capable of affording 

 characters quite as reliable as, and, in many cases, more reliable 

 than, those offered us by leaves, flowers or fruit. For morphologi- 

 cal or physiological study, a knowledge of the characters presented 

 by buds and branches is invaluable. 



A few days ago I came across a very thrifty Pin Oak, about 

 twenty-five years old. Along the smooth, clean trunk, during the 

 past season, a number of weak shoots had grown. I believe we 

 cannot tell how an apical cell, which seems to be required before the 

 growth of the branch can be started, can be formed out of an ordi- 

 nary wood cell and be able to push its way through a layer of bark 

 a quarter of a century old so as to produce the growth of twigs in 

 question. There is an original field here for study as well as a 

 theme for admiration. Perhaps my own discovery, published in the 

 Proceedings of the Academy many years ago, on the nature of 

 warts or excrescences on the trunks of trees, such as we very often 

 see on the Weeping Willow, the Garden Cherry and other trees, 

 may furnish an explanation. It is briefly this: New wood is 

 formed by germination from original wood cells. These are added 

 laterally during the. growing season. The last series of cells born of 

 the mother cells at the end of the season become liber cells, and give 

 the new layer of bark for the coming season. But an occasional 

 cell does not change. It continues to be a wood cell, though sur- 

 rounded by others that have been transformed to bark. It does not 

 separate from its woody matrix, but goes on forming its own addi- 

 tional wood cells, and in the autumn, its layers of bark cells in a sort 

 of colony of its own. These are developed in every direction round 

 the circular matrix, and the excrescence naturally forms a circle. 

 An excrescence, sawn asunder, exhibits the annual growths of wood 

 and the annual deposit of bark, just as the mother trunk does. I 

 have never observed the excrescences make branches. 



The manner in which buds are formed and protected at differ- 

 ent stages of their growth affords endless pleasure. In Lirioden- 

 dron the stipule encloses the younger growth, and, opening the bud, 

 we find the leaf blade has its apex fast in the axis between the 

 branch and the petiole. No one can doubt that the truncate leaf 

 results from its early casting in such a mold. In Magnolia we find 

 the same protection from the stipule, but the petiole is not bent. 



