viii PREFACE 
last at ninety-four — the material to draw upon has been 
superabundant. Nor must the ' Life and Letters of Charles 
Darwin' (briefly cited as CD.) and the 'More Letters of 
Charles Darwin ' (ML.) be forgotten. They are a mine of 
information about the scientific interests of the period and the 
personal relations between the two friends, and my grateful 
acknowledgments to Sir Francis Darwin are repeated here. 
One more name must be mentioned in this place, a name 
which also appears on the title-page. In gathering materials, 
in collating letters, in furnishing personal information, the task 
undertaken with such thoroughness by Lady Hooker has been 
no light one. But if her careful ' spade-work ' has meant much 
for the book, to the \sTiter her active sympathy has meant 
even more. 
L. H. 
October 1917. 
