22 THE ELEMENTARY STRUCTURE OF PLANTS. 



16. Difference between Vegetables and Animals, The distinction be- 

 tween vegetables and minerals is therefore well denned. But 

 the line of demarcation between plants and animals the two 

 kingdoms of organized beings subject to the same general laws 

 is by no means so readily drawn. Ordinarily, there can be no 

 difficulty in distinguishing a vegetable from an animal. But the 

 questionable cases occur on the lower confines of the two king- 

 doms, which descend to forms of the greatest possible simplicity 

 of structure, and to a minuteness of size that baffles observa- 

 tion. Even here the uncertainty is probably attributable rather 

 to the imperfection of our knowledge, than to any confusion of 

 the essential characteristics of the two kinds of beings. It may 

 therefore be less difficult to define them, than to apply the defini- 

 tions to the actual discrimination of the lowest plants from the 

 lowest animals. The essential characteristics of vegetables are 

 doubtless to be sought in the position which the vegetable kingdom 

 occupies between the mineral and the animal, and in the general 

 office it fulfils. Plants, according to the definition given at the 

 outset (1), are those organized beings that live directly upon the 

 mineral kingdom, that grow at the immediate expense of the sur- 

 rounding earth and air. They alone convert inorganic, or mineral, 

 into organic matter ; while animals produce none, but draw their 

 whole sustenance from the organized matter which plants have 

 thus elaborated. Plants, having the most intimate relations with 

 the mineral world, are generally fixed to the earth, or other sub- 

 stance upon which they grow, and the mineral matter on which 

 they feed is taken directly into their system by absorption from 

 without, and assimilated under the influence of light in organs ex- 

 posed to the air ; while animals, endowed with volition and ca- 

 pable of perceiving external impressions, have the power of select- 

 ing the food ready prepared for their nourishment, which is re- 

 ceived into an internal reservoir, or stomach.* The proper tissue 



its own weight two hundred times in twenty-four hours; and such conse- 

 quent power of reproduction, that Linnaeus, perhaps, did not exaggerate, when 

 he affirmed that " three flesh-flies would devour the carcass of a horse as 

 quickly as would a lion." 



* The faculty of locomotion, and even that of " making movements tend- 

 ing to a determinate end," cannot be denied to many plants. Doubtless the 

 sensibility to external impressions, which some plants so strikingly manifest, 

 does not amount to perception; yet, that the lowest animals possess conscious- 



