CHAPTER XIX 



VARIATION AND THE EVOLUTION OF SPECIES 



WHEN we look round upon this land of England, its 

 pleasant fields and placid meadows, its hedgerows, pools, 

 and woods, and the long stretches of purple heath and 

 desolate moor, the question naturally arises, Whence did 

 it all come ? What is the past history of these fields, 

 these woods, these vast hosts of many- tinted flowers ? 

 Is it possible for us to learn something of the previous 

 history of these humble populations their struggles and 

 conquests, to understand why one race has established 

 a dwelling-place here and another there, and to reconstruct 

 in mental vision the part each and all have played in the 

 development of that vegetation which constitutes to-day 

 our native flora ? 



These questions occur to the inquiring mind, but to 

 most there is no answer. Our knowledge, however, is 

 increasing, and every year some light is being thrown upon 

 the dark places. 



The plants which we see around us are unlike those 

 whose remains are preserved to us in the rocks. The 

 further we recede in time, the more unlike the vegeta- 

 tion becomes to that which is living to-day. The number 

 of different forms now inhabiting this country is enor- 

 mous. In the London Catalogue of British Plants 

 over 2,000 species of seed-plants and ferns are enu- 

 merated. Whence arose this great assemblage of plants 

 and this wealth of variation ? Two theories are possible. 

 Either each species is constant and was separately created 

 the Special Creation theory or they have all arisen 

 by modification and variation from pre-existing forms, 

 more or less unlike them, developing under the control of 

 natural laws the Evolution theory. It is now generally 

 agreed that only the latter theory can account for the facts. 



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