The Kinds of Work That Are Done by Plants 79 



At this point, perhaps, some one will rise and declare I am wrong 

 in my statement that work is as real when slow as when swift. 

 But note that I sa}'' as real, not as hard. When a weight of a ton 

 is lifted a foot, no matter bj'^ what means, the work is the same 

 whether done in a day or a minute, although it is over a thousand 

 times harder to do, (to be exact, the power required, is 1440 times 

 greater) in the latter case than the former. But the fact of im- 



FiG. 26. — An asphalt pavement burst upward by the growth of soft-bodied mushrooms, 

 whose conical heads are visible over the wreckage. 



mediate importance is this, that the work is as real in one case 

 as the other. 



We come now to the bond of connection between this matter 

 of plant work and the principal theme of this chapter, viz., — it 

 is a fact of physics, which the reader must long since have learned, 

 that every bit of work of every kind done anyrv^here whatsoever 

 in nature, whether in a plant, or an engine, or the skies, or the 

 thinking brain of a man, requires for its accomplishment the 

 presence and expenditure of energy, which is the source of all 

 power. The reader, of course, knows what energy is, — the en- 

 tity in Nature, and the only one, that produces motion by which 



