302 Geographical Distribution of Plants 



manner, as was stated by Forbes, followed, alas, by Hooker, and 

 caricatured by Wollaston and [Andrew] Murray 1 ." The transport 

 question thus became of enormously enhanced importance. We need 

 not be surprised then at his writing to Lyell in 1856: "I cannot 

 avoid thinking that Forbes' 'Atlantis' was an ill-service to science, 

 as checking a close study of means of dissemination 2 ," and Darwin 

 spared no pains to extend our knowledge of them. He implores 

 Hooker, ten years later, to "admit how little is known on the 

 subject," and summarises with some satisfaction what he had himself 

 achieved: "Remember how recently you and others thought that 

 salt water would soon kill seeds.... Remember that no one knew that 

 seeds would remain for many hours in the crops of birds and retain 

 their vitality; that fish eat seeds, and that when the fish are de- 

 voured by birds the seeds can germinate, etc. Remember that 

 every year many birds are blown to Madeira and to the Bermudas. 

 Remember that dust is blown 1000 miles across the Atlantic 3 ." 



It has always been the fashion to minimise Darwin's conclusions, 

 and these have not escaped objection. The advocatns diaboli has a 

 useful function in science. But in attacking Darwin his brief is 

 generally found to be founded on a slender basis of facts. Thus Winge 

 and Knud Andersen have examined many thousands of migratory birds 

 and found " that their crops and stomachs were always empty. They 

 never observed any seeds adhering to the feathers, beaks or feet of 

 the birds 4 ." The most considerable investigation of the problem of 

 Plant Dispersal since Darwin is that of Guppy. He gives a striking 

 illustration of how easily an observer may be led into error by relying 

 on negative evidence. 



"When Ekstam published, in 1895, the results of his observations 

 on the plants of Nova Zembla, he observed that he possessed no data 

 to show whether swimming and wading birds fed on berries ; and he 

 attached all importance to dispersal by winds. On subsequently 

 visiting Spitzbergen he must have been at first inclined, therefore, 

 to the opinion of Nathorst, who, having found only a solitary species 

 of bird (a snow-sparrow) in that region, naturally concluded that 

 birds had been of no importance as agents in the plant-stocking. 

 However, Ekstam's opportunities w r ere greater, and he tells us that 

 in the craws of six specimens of Lagopus hyperborciis shot in Spitz- 

 bergen in August he found represented almost 25 per cent, of the 

 usual phanerogamic flora of that region in the form of fruits, seeds, 

 bulbils, flower-buds, leaf-buds, &c " 



" The result of Ekstam's observations in Spitzbergen was to lead 

 him to attach a very considerable importance in plant dispersal to 



1 Life and Letters, in. p. 230. 2 Ibid. n. p. 78. 3 More Letters, i. p. 483. 



4 B. F. Scbarff, European Animals, p. 64, London, 1907. 



