CHAPTER XIII 

 THE PLANT'S PLACE IN NATURE 



197. The three kingdoms. It has long been the general 

 opinion that all natural objects fall readily into three main 

 groups or kingdoms — the mineral, the vegetable, and the 

 animal. Over a century ago the characteristics of each 

 kingdom as understood at the time, were given by Linnaeus 

 in his famous aphorism: ''Minerals grow; plants grow and 

 live; animals grow, live, and feel."' This threefold division 

 is still recognized as convenient, and the distinctions given 

 are admitted as valid to a considerable extent; but that a 

 mineral grows in essentially the same way as a plant, and 

 that a plant lacks any quality that is found in all animals, 

 would not generally be admitted b}^ the naturalists of to-day. 

 In order to understand modern views regarding the plant's 

 place in Nature we need to consider what is meant by grow- 

 ing, living, and feeling. 



By "growth" Linnaeus seems to have meant merely increase 

 in size. Yet is not the enlargement of a seaweed or a fish 

 essentially different from the so-called growth of a salt crystal 

 in concentrated brine? The crj'stal gets larger simply by 

 additions upon the outside, while the living body increases 

 in size by the incorporation within itself of substances de- 

 rived from without. IMoreover, the crystal as it enlarges 

 remains substantially the same throughout, and all the parts 

 behave alike. In a growing body on the contrary there is a 

 progressive differentiation of parts and functions. Hence 

 we cannot say that a mineral grows in the same sense that 

 an organism grows. 



But does not Linnaeus express the differences above in- 



^ Lapides crescnnt; vegetahilia crescunt et I'ivunt; animalia crescunt, 

 vivunl el sentiuiil. 



561 



