CH. IX.] DEATH AND DECOMPOSITION. 331 



their veiy lowest parts, whereas apotheme is inju- 

 rious to them if they are gro-^ii in a solution of it, 

 and the minutest analyzers have failed to detect it 

 even within the extreme vessels of roots. 



Acids ai'e antiseptic, and retard the decay of 

 vegetable matters, which explains why the woody 

 fibre in peat soils remain.' so long unchanged, for 

 those soils abound in gallic and other acids. 



Alkalies, on the other hand, accelerate vegetable 

 decomposition; and these being present in calca- 

 reous soils, is one reason that manures are sooner ex- 

 hausted in them than in any other. Another reason 

 for this rapid consumption is, that in calcareous and 

 siliceous soils, the air easily penetrates, and the rapid 

 progress of decay depends in a great measure upon 

 the free access of oxygen gas. Such access is less easy 

 to manures buried in clayey soils ; and, as a conse- 

 quence, manures in them are much more permanent. 



Such is the progress, such the phenomena, attend- 

 ant upon the death of plants ; and but one more re- 

 lative question remains for our consideration — Can 

 death be averted from plants ? Can they be made, 

 by mans devices, an exception to that decree of 

 limited existence, which extends over all other or- 

 ganized creatures ? 



Those who assert that grafting completely renovates 

 the scion, maintain the affirmative. From these I 

 totally differ ; for though it is happily true that 



