574 THE PLANT'S PLACE IN NATURE 



on the other liand, is generally sohd and so requires to be dis- 

 solved in a digestive cavity within the body before absorp- 

 tion is possible. Plants which can make their own food from 

 materials always at hand have no such need for traveling 

 about in search of food as most animals have; and while 

 food-seeking calls for the special sensitiveness which Linnseus 

 termed feeling, food-making involves only such manifesta- 

 tions of irritability as might easily escape his notice. A 

 typical plant is thus a sedentary food-maker, a typical 

 animal being a roving eater. It is only when plants lose 

 more or less their power of making food, and animals their 

 power of locomotion that doubt arises as to their kingdom, 

 and then the question has to be decided not so much by 

 rules and definitions, as by evidences of their kinship to un- 

 doubted examples of vegetable or animal life. 



A Bacterium, for example, is classed as a plant because of re- 

 semblances to a Nostoc which outweigh its animal-like motility and 

 dependence ujpon organic food. If a Bacterium should develop a 

 digestive cavity for the reception of its food we should say it had 

 become an animal. 



The most fundamental difference between plants and 

 animals appears thus to lie in the ways they prefer to get their 

 food — the vegetable way being to make the best of what 

 comes to it, the animal choosing rather to capture what 

 plants have made. Returning to our simile of the boats it 

 might be said that the vegetable craft choose to anchor in a 

 stream of materials which they organize into food, while 

 the animal craft navigate the stream and repair their losses 

 entirely from other vessels. A modern revision of the aph- 

 orism of Linnseus, still, however, confessedly inaccurate, 

 might read: — minerals crystalhze; plants organize or re- 

 organize materials which they absorb; animals reorganize 

 food which they have swallowed. 



200. Plants in general. The foregoing reflections upon 

 the way natural objects are related to one another are in- 

 tended especially to emphasize the pivotal place which plants 

 hold in the economy of nature. It is now believed that the 

 wide and rich possibilities of earthly life could not have 

 Ix^en gained or maintained \\dthout plants. Plants were 



