424 HOOKEK'S POSITION AS BOTANIST 



century after Hooker first set foot in India. It is upon such 

 foundations that Hooker's reputation as a great constructive 

 thinker is securely based. 



The first named of these Essays will probably be estimated 

 as the most notable of them all in the History of Science. It 

 was completed in November 1859, barely a year after the 

 joint communications of Darwin and Wallace to the Linnean 

 Society, and before the ' Origin of Species ' had appeared. It 

 was to this Essay that Darwin referred when he wrote that 

 * Hooker has come round, and will publish his belief soon.' 

 But this publication of his belief was not merely an echo of 

 assent to Darwin's own opinions. It was a reasoned statement 

 advanced upon the basis of his ' own self -thought,' and his 

 own wide systematic and geographical experience. From these 

 sources he drew for himself support for the * hypothesis that 

 species are derivative, and mutable.' He points out how the 

 natural history of Australia seemed specially suited to test 

 such a theory, on account of the comparative uniformity of the 

 physical features being accompanied by a great variety in its 

 Flora, and the peculiarity of both its Fauna and Flora as 

 compared with other countries. After the test had been made, 

 on the basis of study of some 8000 species, their characters, 

 their spread, and their relations to those of other lands, he 

 concludes decisively in favour of mutability and a doctrine 

 of progression. 



How highly this Essay was esteemed by his contemporaries 

 is shown by the expressions of Lyell and of Darwin. The former 

 writes : 



I have just finished the reading of your splendid Essay 

 on the Origin of Species, as illustrated by your wide botanical 

 experience, and think it goes far. to raise the variety-making 

 hypothesis to the rank of a theory, as accounting for the 

 manner in which new species enter the world. 



Darwin wrote : 



I have finished your Essay. To my judgment it is by 

 far the grandest and most interesting essay on subjects of 

 the nature discussed I have ever read* 



