12 STRUCTURE OF VEGETABLES. 



Physiologists have freqently busied themselves in endeav- 

 oring to discover what it is, which distinguishes precisely 

 the two living kingdoms from each other. They have endeav- 

 ored in vain, because they have expected to find this dis- 

 tinction in one single principle, which would admit of a short, 

 plain, and specific definition. Such a principle can be only 

 ideal. It does not exist even with regard to the mineral and 

 living classes of substances. It would not be, difficult to con- 

 found the boundaries of living and dead matter, in the same 

 way as those of vegetable and animal matter. The distinc- 

 tion must be sought in the general structure, the general 

 mode of existence, and the purposes of existence in the two. 

 And in a few words we may say, that animals differ from 

 plants in being furnished with internal organs for the purpose 

 of digesting food, instead of absorbing it by roots from the 

 earth; in being furnished with organs which render them 

 capable of moving from place to place, or at least of moving 

 one part of their bodies on some other part ; in having pow- 

 ers of sensation, perception, and volition, by which they ac- 

 quire a knowledge of the existence and qualities of other 

 bodies besides themselves, and form some sort of relation or 

 connection with them ; and in being obviously intended, by 

 the possession of these organs and powers, to be conscious of 

 and to enjoy existence. 



CHAPTER II. 



GENERAL REMARKS ON THE STRUCTURE OF VEGETABLES. 



IN considering plants and animals with a view to the de- 

 scription of their structure and organs, there is one remarka- 

 ble circumstance worthy of attention at first, viz. that while 

 the animal kingdom exhibits a great variety between different 

 classes in respect to the perfection, completeness, and com- 

 plexity of their structure, and the number of their functions ; 

 so that a regular series is formed, ascending from the lowest 

 and most imperfect worm possessed of no faculties but those 

 of feeling and moving, up to quadrupeds with all their won- 

 derful and varied powers the vegetable kingdom, on the co- 

 trary, exhibits but little of this sort of variety. Plants are 

 nearly all alike with regard to the organs they possess and 

 the functions they perform. On the one hand, the polype 



