Nature, Longemty^ and She of Trees. 6 



tion of them, however, here made to the questions already 

 specified, does not appear to have entered into the view of 

 that ingenious physiologist. So far, at least, as I can gather 

 from the writings of Richard, Lindley, and others, M. Thouars 

 seems to have applied them only in explanation of the nature 

 and the mode of formation of the woody layer annually pro- 

 duced in exogenous trees. At all events, both the principles 

 themselves, and the application I have made of them, mani- 

 festly differ from the views commonly entertained as to the 

 nature and the natural longevity and size of trees. Nor can 

 I find anything amounting to a distinct recognition or de- 

 tailed exposition of them in any of our systematic works on 

 Botany. If they are correct, however, their scientific interest 

 and importance clearly demand this, even in the merest out- 

 line that can be given of vegetable physiology. And as the 

 evidence in support of them appears to me conclusive, I am 

 inclined to hope that the present attempt to bring them pro- 

 minently forward may not be deemed undeserving of atten- ^^ 

 tion.* 



In proceeding to vindicate, and more fully to illustrate, 

 those principles, it is desirable, in the first instance, to in- 

 quire what is known in regard to the natural longevity, and 

 the natural size of trees, according to the view usually taken 

 of the nature of this class of objects. The inquiry, by shew- 

 ing how imperfect that knowledge is, and how difiicult it is 

 to impart to it any character of precision, will naturally pave 

 the way to the consideration of the principles in question, and 

 probably dispose to a more cordial reception of them. 



* Since these observations were put together, I have seen a foot-note in 

 Roget's Bridgewater Treatise (vol. ii., pp. 555-6, 3d Ed.), wherein the views 

 promulgated in the text are briefly hinted at, on the high authority of De 

 Candole. More recently, I have had the satisfaction of finding a clear and dis- 

 tinct statement of them in Dr Carpenter's Manual of Physiology. " A forest 

 tree may go on extending itself to an almost indefinite extent ;" " but the increase 

 is produced, not so much by the continued development of the individual, as by 

 the continued production of new individuals which remain in connection with 

 the original. Thus, each bud of a tree may be regarded as a distinct individual ; 

 because, if placed under favourable circumstances, it can maintain its life by 

 itself, and can perform all the actions proper to the species." — Pp. 2, 3. 



