70 SYLVA AMERICANA. 



the only rational method of arriving at any certainty concerning 

 the laws of vegetable economy. Upon this subject Dr. Hales 

 judiciously observes, " that as the growth and preservation of 

 vegetable life is promoted and maintained, as in animals, by the 

 very plentiful and regular motion of their fluids, which are the 

 vehicles ordained by nature to carry nutriment to every part, it 

 is, therefore, reasonable to hope, that in them also, by the same 

 method of inquiry, considerable discoveries may in time be 

 made ; there being, in many respects, a great analogy between 

 plants and animals." 



CHAP. IV. 



Casualties Affecting the Life of Vegetables. 



As plants are, like animals, organized and living beings, they 

 are, like animals also, liable to such accidental injuries and 

 disorders as may affect the health and vigor, or occasion the 

 death of the individual ; which is at any rate eventually effected 

 by means of the natural decay and final extinction of the vital 

 principle. Hence the subject of vegetable casualties divides 

 itself into the three following heads : wounds, diseases and natural 

 decay. 



Wound s. 



A wound is a forcible separation of the solid parts of the 

 plant effected by means of some external cause. It may be 

 intentional, as in the case of incision, boring, girdling, grafting, 

 pruning, felling and such like operations ; or it may be acciden- 

 tal, as in the case of injuries sustained by the rubbing or browsing 

 of cattle ; by the bite and depredation of insects, hares and rab- 

 bits ; by lightning ; by weight of fruit ; or by violent storms of 

 wind, hail and snow. 



1 . Incision. Incisions are sometimes necessary to the health 



