VEGETABLE PHYSIOLOGY. 11 



continued, preserve llieir various functions in full activity and 

 similitude, in whatever temperature, season, soil, or aspect, they 

 may be placed ; and a loss of any of their important organs, or 

 a considerable interruption to the functions of the others, very 

 frequently terminates in their general dissolution. 



Vegetables, again, have not a brain and nervous system to 

 endow them with perceptive powers, or, as far as we can judge, 

 with sensation ; nor muscles to promote their locomotion, so 

 necessary to most animals which are to make choice of their 

 food, and whose means of supply are not confined to a narrow 

 circle as in vegetables, in which nature by their peculiar 

 mechanism, has bestowed on them the means of obtaining their 

 nourishment from the soil which first gave them birth. For 

 this purpose the latter are permanently fixed to one spot in the 

 earth, and the vital spark having once been excited, their 

 different movements are rendered dependent upon principles, in 

 which the will has no concern, and where perception cannot be 

 required. 



These reflections necessarily lead us to a consideration of the 

 structure and functions of vegetables, in which the analogy of 

 the two kingdoms will be further illustrated, and of the line of 

 distinction, we hope, satisfactorily explained. 



To consider vegetable physiology in all its relative bearings, 

 it will be requisite to divide the subject into four distinct heads. 

 First, the structure and functions of those parts of a vegetable 

 which contribute to its nourishment and preservation, including 

 the root, trunk, branches and leaves. Secondly, of those organs 

 which are necessary to its reproduction, and these have reference 

 to the flower, fruit and seed. Thirdly, the process of generation 

 and germination, of the food and agents effecting its growth, and 

 the formation and completion of a new plant. And lastly, the 

 casualties affecting the life of vegetables, consisting of wounds, 

 diseases, natural decay and renovation. 



But previously to entering into a particular description of the 

 several organs, it will be proper to observe that vegetables, like 

 animals, are composed of fluids and solids. The fluid parts 

 produce those which are solid ; and the only aliment . which 



