6] FOUNDATIONS OF MODERN DISTRIBUTIONS 



169 



Fig. 45. — Maps illustrating 'Continental drift' and the proximity of land-masses 

 as apparently affecting floristic richness. A, reconstructions of the map of the 

 world at three stages according to the theory of continental drift, the thinly stippled 

 areas being shallow seas, while present-day rivers, etc., are shown merely for pur- 

 poses of orientation (after Wegener); B, comparison of areas and floras of islands 

 in relation to the proximity of major land-masses and their floristic richness 

 (prepared by W. T. Steam). 



