58 VITAL FUNCTIONS OF PLANTS. [LECT. II, 



root left in the earth, it will again shoot forth new 

 stems, branches, and leaves ; and if the bark of 

 a plant be partially cut away, it will be reproduced. 

 This power, however, is not possessed by every 

 plant, nor is reproduction observed to take place 

 in every part of any plant. All those plants which 

 may be regarded as compound beings (as trees, 

 for instance, each bud of which seems to possess 

 a distinct life), may have parts cut from them, 

 which, if stuck into the ground under favourable 

 circumstances, will throw out roots and grow, 

 and each piece become an entire plant, similar to 

 that from which it was cut. In some plants, even 

 the leaves possess such a degree of distinct vitality, 

 that any portion of a leaf, provided it contain 

 part of the margin, when stuck into the ground, 

 throws out radicles and becomes an entire and 

 perfect plant, resembling that from which it was 

 taken. The Bryophyllum calytinum is an ex- 

 ample of this fact. But those which are consi- 

 dered as simple plants cannot be much mutilated 

 without suffering. If the Cabbage, or head of a 

 Palm, for example, be cut off, the plant soon dies; 

 or if a Fir, or other resinous plant, be much prun- 

 ed or cut down, no new shoots are produced ; and 

 if a leaf of any plant be once mutilated, it never 

 again recovers that portion which it has lost. In 

 this respect plants do not differ from animals. If 

 a Polypus, and some kind of worms, be cut in 



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