138 HOW PLANTS GROW. [lESSON 22. 



370. This completes the circle, and brings our vegetable history 

 round to its starting-point in the Second Lesson ; namely, The 

 Growth of the Plant from the Seed. 



LESSON XXII. 



HOW PLANTS GROW. 



380. A PLANT grows from the seed, and from a tiny embryo, like 

 that of the Maple (Fig. 327), becomes perhaps a large tree, pro- 

 ducing every year a crop of seeds, to grow in their turn in the same 

 way. But how does the plant grow ? A little seedling, weighing 

 only two or tiiree grains, often doubles its weight every week of its 

 early growth, and in time may develop into a huge bulk, of many 

 tons' weight of vegetable matter. How is this done ? What is vege- 

 table matter ? Where did it all come from ? And by what means 

 is it increased and accumulated in plants ? Such questions as these 

 will now naturally arise in any inquiring mind ; and we must try to 

 answer them. 



381. Growth is tlie increase of a living thing in size and substance. 

 It appears so natural to us that plants and animals should grow, that 

 people rarely think of it as requiring any explanation. They say 

 that a thing is so because it grew so. Still we wish to know how 

 the growth takes place. 



382. Now, in the foregoing Lessons we explained the whole struc- 

 ture of the plant, with all its organs, by beginning with the seedling 

 pUntlet, and following it onward in its development through the 



FIG. 327. Germinating enil)ryo of a Maple. 



