What Do Both Plants and Animals Do? 



Activities of Animals' Every familiar animal moves from place to 

 place. It also moves its parts, as in striking or biting. To us such move- 

 ments at once suggest other activities. Mouth movements suggest eating. 

 Eye movements suggest searching and watching. The movements of an in- 

 sect's antennae suggest groping or "feeling", as we feel with our fingers. 



From our past experience we know that food is related to growing. And 

 while neither a person nor any other animal enlarges under our eyes, we 

 know that each must have grown, for neither was born full size. And 

 that suggests another thing that animals do: they reproduce. There is also 

 about each animal something that makes it move or change its movements 

 when certain outside conditions act upon its feelers, or eyes, or ears, for 

 example. 



Some of the animals we know eat one kind of food, some another. Some 

 grow rapidly, some slowly. But all take in food and grow. So, too, animals 

 differ as to how sensitive they are, as to what kinds of conditions influence 

 them, and as to how rapidly or how vigorously they move. But all are 

 sensitive to changes, and all do move. And all animals originate from 

 other animals of the same kind. 



Activities of Plants What now of plants ? We know that plants grow. 

 When we want new plants for any purpose, we usually look to getting 

 them from seeds, which in turn come from other plants. That is, plants 

 reproduce themselves. But do they also move } Is a plant sensitive to what 

 goes on around it? 



Most of us have not noticed whether plants do really move or whether 

 they respond to changes in their surroundings. Certainly plants do not 

 reach out and grasp food, as do the kitten and the baby, for example. Nor 

 does the plant eat with a mouth. Still the very fact of growing, which de- 

 pends upon taking in food, implies some movement. The plant does take 

 materials into itself from its surroundings, by way of the roots and by way 

 of the leaves. And it does move, or transport, these materials from one part 

 to another. 



Most of the movements in a plant are slow and minute, so that we should 

 need a microscope to observe them directly. But we can easily observe a 

 rapid movement of the leaves of a disturbed sensitive-plant. And we can 

 observe slower, yet very distinct, turnings of many common plants toward 

 the light (see illustration, p. 257). These movements show us that plants 

 are sensitive to what is going on around them. 



^See No. 2, p. 27. 

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