a SCIENCE PRIMERS, [§ i. 



■ > ' .■■■ I.I ■ ■ , I 



own accord, so can a dog, so can any animal as long 

 as it is alive. If you leave a stone in any particular 

 spot, you expect to find the stone there when you 

 come to it again a long time afterwards ; if you do 

 not, you say somebody or something has moved 

 it. But if you put a sparrow or mouse on the grass 

 plot, you know that directly your back is turned it 

 will be off. 



All animals move of themselves. But only so long 

 as they are alive. When you find the body of a 

 snake on the road, the first thing you do is to stir it 

 with a stick. If it moves only as you move it, and 

 as far as you move it, just as a bit of rope might do, 

 you say it is dead. But if, when you touch it, it stirs 

 of itself, wriggles about, and perhaps at last glides 

 away, you know it is alive. Every living animal, of 

 whatever kind, from yourself down to the tiniest 

 creature that sw^'ms about in a little pool of water 

 and cannot be seen without a microscope, mc^es of 

 itself. Left to itself, it moves and rests, rests and 

 moves; stirred by anything, away it goes, running, 

 flying, creeping, crawling, or swimming. 



Something of the kmd sometimes happens with 

 lifeless things. When a stone is carefully balanced 

 on the top of a high wall, a mere touch will send it 

 toppling down to the ground. But when it has 

 reached the ground it stops there, and if you want to 

 repeat the trick you must carry the stone up to the 

 top of the wall again. You know the toy made like 

 a mouse, which, when you touch it in a particular 

 place, runs away apparently of its own accord, as if 

 it were alive. But it soon stops, and when it has 

 Stopped you may touch Jt again and again without 





