CD had encouraged Hooker to compile his materials into a general work on botany (see letters to J. D. Hooker, 8 February [1860] and 12 March [1860]). Hooker wrote on this subject to John Stevens Henslow in March 1860: ‘Murray and others are very anxious, I understand, that I should bring out a Darwinian book on Botany—a sort of elementary book on Classification, Distribution, and origin of species. I am dubious and considering. I think I could make it a good instructional one with woodcuts illustrating all sorts of transitional forms, independent of all theory.’ (L. Huxley ed. 1918, 1: 535).