48 AMEniCAN POltOLOGT. 



have but a, limited period of existence, be tbat longer or 

 shorter. Reasoning from the analo<?ies of animal life this, 

 would ajDpear very probable, for it is well known that in- 

 dividuals of different species all have a definite period of 

 life, some quite brief, others quite extended, beyond which 

 they do not survive. But with our modern views of vege- 

 tation, though we know that all perennial pLants do even- 

 tually die and molder away to the dust from whence they 

 were ci-eated, and that many trees of our own planting 

 come to an untimely end, while we yet survive to observe 

 their decay, still, we can see no reason why a tree or parts 

 of a tree taken from it, and placed under circumstances 

 favorable to its growth from time to time, may not be sem- 

 piternal. Harvey has placed this matter in a correct 

 liglit, by showing that the true life and history of a trcj 

 is in the buds, which are annual, while tli'e tree itself is 

 the connecting link between them and the ground. Any 

 portion of such a compound existence, grafted upon an- 

 other stock, or planted immediately in the ground itself 

 and established ujjon its own roots, will produce a new 

 tree like the first, being furnished with supplies of nour- 

 ishment it may grow indefinitely while retaining all the 

 qualities of the parent stock — if that be healthy and vig- 

 orous so will this — indeed new life and vigor often seem to 

 be imparted by a congenial thrifty stock, and a fertile soil, 

 ■so that there does not aj^pear to be any reason why the 

 variety should ever run out and disappear. 



The distinguislied Thomas Andrew Knight, President 

 of the London 11— .>■ ;*ural Society, was one of tlie lead- 

 ing advocates of the theory that varieties would neces- 

 sarily run out and disappear as it were by exhaustion. 



