2 Dr Harvey's OJbservations on the 



such, the cessation of its vital actions, and the loss of its vital 

 properties, is a fundamental law of the constitution of every 

 living being. The provisions to which it owes its existence, 

 and by which its vital actions are for a time performed, neces- 

 sarily involve the extinction of its vital powers. Such changes 

 are gradually wrought in it by the very agency of its vitality 

 as are ultimately incompatible with the longer continuance 

 of life, and death follows as a matter of course. And those 

 changes are attended by, if they do not essentially consist in, 

 a gradually increasing languor or sluggishness in the activity 

 of the vital processes, and by a corresponding density and 

 rigidity of the textures composing the organism — constituting 

 a state to which the name of old age is given, which obtains 

 uniformly when life is not prematurely cut short, and is in- 

 dicative of the approach of death. Again, all organized beings 

 have a definite size or bulk of organism. Of lifeless inorganic 

 bodies, it cannot be affirmed that they possess any such 

 quality, being smaller or larger to any conceivable extent, 

 according as circumstances may determine. It is otherwise, 

 however, with animal and vegetable organisms, which have 

 naturally a fixed or standard size to which they grow, and 

 from which they never greatly deviate. This fact in their 

 history may not perhaps be so obviously true as that of a 

 limited duration of life ; nevertheless it can be shewn to be 

 an equally general one, and the exceptions to it to be only 

 apparent, not real. 



But, acquiescing in the truth and universality of the prin- 

 ciple now referred to, it may be confidently asserted in regard 

 to trees, that, on the assumption stated as to their nature — 

 to wit, that every individual tree is an individual plant — there 

 are many facts in their history which it is difficult to recon- 

 cile with that principle ; and, generally, that nothing definite 

 or satisfactory has yet been ascertained respecting either the 

 natural longevity or the natural size of any one species of 

 tree, — a circumstance which contrasts remarkably with the 

 precision of our knowledge, so far as it goes, as to these 

 particulars in the case of animals, and the more, from the 

 facilities that exist for making observations upon trees. 



