II] GEOGRAPHICAL DISTRIBUTION 25 



of his study of distribution in the Galapagos Islands 

 that Darwin determined to 'collect blindly every 

 sort of fact which bears anyway on what are species.' 

 The acceptance of the view^ 'that each species was 

 first produced within a single region '(19), raises the 

 subject of geographical distribution to a far higher 

 plane than it occupied in pre-Darwinian days. Al- 

 though most people are familiar with some of the 

 commoner means by which plants are able to colonise 

 new ground through the adaptation of their fruits and 

 seeds to various methods of transport, the conception 

 of a plant as a stationary organism tends to prevent 

 due allowance being made for the comparative 

 facility with which, in the course of successive 

 generations, a species is able to wander from place 

 to place. The individual animal is endowed with 

 powers of locomotion enabling it to seek new feeding- 

 grounds and to avoid enemies ; but with the 

 exception of some of the simplest forms a plant 

 cannot move — 'le niatin la laisse oii la trouve le 

 soir.' ^ 



The rate of travel may or may not be rapid, but 

 in a comparatively short time, if the conditions are 

 favourable, a tree may spread over a wide area. 

 Mr Ridley, Director of the Botanic Gardens, Singa- 

 pore, writes as follows in reference to the rate of 

 travel of one of the common Malayan trees {Shorea 

 leprosula), which bears Avinged fruits particularly 



