302 Geographical Distribution of Plants 
Manner, as was stated by Forbes, followed, alas, by Hooker, and 
caricatured by Wollaston and [Andrew] Murray’.” 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?,” 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®.” 
It has always been the fashion to minimise Darwin’s conclusions, 
and these have not escaped objection. The advocatus 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*.” 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 were greater, and he tells us that ~ 
in the craws of six specimens of Lagopus hyperboreus 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, 11, p. 230. 2 Ibid. 1. p. 78. 3 More Letters, 1. p. 483. 
4 BR. F. Scharff, European Animals, p. 64, London, 1907. 
