PART II 



THE APPLICATION OF AGE AND AREA 



TO THE FLORA OF THE WORLD 



AND ITS IM PLICA TIONS 



CHAPTER X 



THE POSITION OF THE AGE AND AREA THEORY 

 By H. B. GuppY, M.B., F.R.S. 



V\ E would sometimes infer that there is only one way of reaard- 

 ing the central problem of Plant-Distributioji. If tjiis wer'e so 

 distribution would stand alone among the great studies of plant- 

 hfe, and It would be particularly unattractive and uninteresting 

 Generally speaking, the more numerous the standpoints the 

 more complete will be our grasp of the problem. The surveyor 

 who has the most accurate conceptions of the extent and out- 

 hnes of a great mountain range will be the man who has viewed 

 It from the greatest variety of stations, and so it will be with the 

 student of distribution. 



The fewer limitations we impose upon ourselves at the start 

 the better progress shall we make. Some are ine\itable, but they 

 should be light easy burdens that do not gall. Thus when we find 

 ourselves constrained to associate our point of view with the 

 story of E^•olution, we are at once confronted with the query as 

 to the kind of evolution implied. What is the genetic sequence 

 in the scheme of the ordinal, tribal, generic, specific, and varietal 

 types? It is possible to hold views in this connection that are 

 as far asunder as the poles. In the case where we begin with the 

 larger groups we ha^ e evolution on a plane, or differentiation 

 pure nnd simple. The basic principle here involved, the change 

 from the Simple to the Complex, from the General to the Par- 

 ticular, from the Homogeneous to the Heterogeneous, is at the 

 back of the development of life on the earth. It is symbolised 

 m all natural systems of classification and in the daily practice 

 of the systematist, and was a part of the faith of the old 

 philosophers. 



