THE DEVELOPMENT OP THE PLANT 49 



CHAPTER IV 

 THE DEVELOPMENT OP THE PLANT 



IN the course of the preceding chapter many a reader 

 will have felt that we were merely preparing the theatre, 

 as it were, for the drama of the evolution of life. In one 

 sense that is perfectly true, but we were really doing 

 very much more, A large amount of the interest of the 

 story of evolution is lost when the earth is regarded as 

 the passive stage of the transformations of living things. 

 Those physical changes in the earth's story which I 

 selected from the long geological record have had a 

 most profound effect upon organisms, and reveal half 

 the secret of their progress when they are attentively 

 considered. The strict specialisation of sciences in our 

 time an essential condition of their advance causes 

 many to overlook the vital connection between geological 

 changes and biological evolution, and it must be our task 

 to study them in close conjunction. 



It is, therefore, in the light of the preceding story of 

 the earth that we will now follow the long procession of 

 organic forms that has passed over the surface of our 

 planet during the last fifty million years or more. 

 Further, in order to do so with any degree of instructive- 

 ness, we must make separate surveys of the evolution of 

 the plant and the animal. We shall find that there has 

 been a very close connection between them; but the 

 two great branches of the tree of life diverge so widely, 

 once they have parted from the primitive stock, that it 

 is somewhat confusing to attempt to follow both 

 together. 



