SECT. III. NATURAL DECAY. 5 13 



And in the sloughing of the diseased part there is 

 yet another circumstance clashing with the analogy 

 that is here instituted. The part supplying the 

 place of the slough, or throwing it off, is formed or 

 exists already formed immediately beneath it, and 

 is precisely of the same character with what the 

 slough originally was ; which slough it pushes off as 

 it comes itself to maturity, or acquires strength suffi- 

 cient for the effort. But the leaves fall off when they 

 have reached maturity of their own accord, without 

 being at all pushed off by the new ones, which are 

 yet merely in embryo, and do not even occupy the 

 place of the old leaves, but are only formed conti- 

 guous to them, except in the case of the Plane-tree, 

 the new leaf of which is formed precisely under the 

 base of the foot-stalk of the old leaf: and yet I would 

 not call the fall of that leaf sloughing, because the 

 new leaf does not after all push off the old one ; and 

 because there is here, as in other cases, the same na- 

 tural articulation uniting the leaf to the branch or 

 stem, and rendering it a distinct organ that is ulti- 

 mately and spontaneously to detach itself from the 

 plant. Not that there exists no example whatever 

 of vegetable sloughing, which the same tree will also 

 furnish in the annual or rather continual exfoliation 

 of its bark, but that the fall of the leaf does not seem 

 to me to afford that example. 



I can foresee an objection that may be urged 

 against the above argument from the fact of the 

 sloughing of the entire skin of the snake, and other 



VOL. n. 2 L 



