FALL OF THE LEAF. 341 



rotten. The only remedy in this case is 

 speedy amputation below the diseased part. 

 Sometimes the force of the vital principle 

 makes a stand, as it were, against the en- 

 croaching disease, and throws off the infected 

 joint or branch. Such is the account given 

 by Thiery, which evinces a power in vege- 

 tables precisely adequate to that of the ani- 

 inal constitution, by which an injured or dis- 

 eased part is, by an effort of Nature, thrown 

 off to preserve the rest. 



Nor need we travel to Mexico to find ex- 

 amples of this. Every deciduous tree or 

 shrub exhibits the very same phenomenon ; 

 for the fall of their decaying foliage in au- 

 tumn, leaving the branches and young buds 

 vigorous and healthy, can be explained in no 

 other way. Yet Du Hamel laboured in vain 

 to account for the fall of the leaf* ; nor is it 

 wonderful that he or any body else, who en- 

 deavours to explain the physiology of vege- 

 tables or of animals according to one prin- 

 ciple only, whether it be mechanical or che- 

 mical, should entirely fail. To consider the 

 fall of leaves in autumn as a sloughing, or 



* See his Phys. des Arhres, v. l r 127. 



