CHAPTER III 



A GREEN LEAF 



There are really no "marvels" in Nature, 

 because everything which is has its proper place 

 in a sequence of simple cause and effect. Yet we 

 are so accustomed to judge things by what we 

 can see of them with our unaided eyes that it is 

 hard to hold back the exclamation of surprise and 

 wonder when the microscope reveals to us un- 

 suspected complexities in structures which we 

 have previously regarded as simple and insignifi- 

 cant. Take a green leaf for example. Nine out 

 of ten of us are satisfied to know that it is the 

 habit of plants to be covered with green leaves, 

 which usually fall off when the cold of winter nips 

 them but grow again in spring. To ask why 

 plants have leaves seems as idle a question as 

 why birds have feathers, or fishes scales : so 

 when, under the microscope the elaborate struc- 

 ture and important functions of leaves are made 

 plain — when we see that, not only the life of 

 plants, but the life of all things that live depends 



