en. ii. J ORCHIDS. 47 



done to the best of my abilities, and critics may say what 

 they like, but they cannot destroy this conviction. 



During the two last months of 1859 I was fully occupied 

 in preparing a second edition of the Origin, and by an 

 enormous correspondence. On January 1st, 1860, I began 

 arranging my notes for my Avork on the Variation of Ani- 

 mals and Plants under Domestication ; but it was not pub- 

 lished until the beginning of 1868 ; the delay having been 

 caused partly by frequent illnesses, one of which lasted 

 seven months, and partly by being tempted to publish on 

 other subjects which at the time interested me more. 



On May loth, 1862, my little book on the Fertilisation of 

 Orchids, which cost me ten months' work, was published: 

 most of the facts had been slowly accumulated during sev- 

 eral previous years. During the summer of 1839, and, I be- 

 lieve, during the previous summer, I was led to attend to the 

 cross-fertilisation of flowers by the aid of insects, from hav- 

 ing come to the conclusion in my speculations on the origin 

 of species, that crossing played an important part in keep- 

 ing specific forms constant. I attended to the subject more 

 or less during every subsequent summer ; and my interest 

 in it was greatly enhanced by having procured and read in 

 November 1841, through the advice of Robert Brown, a 

 copy of C. K. Sprengel's wonderful book, Das entdeckte 

 Geheimniss der Natur. For some years before 1862 I had 

 specially attended to the fertilisation of our British or- 

 chids ; and it seemed to me the best plan to prepare as com- 

 plete a treatise on this group of plants as well as I could, 

 rather than to utilise the great mass of matter which I had 

 slowly collected with respect to other plants. 



My resolve proved a wise one ; for since the appearance 

 of my book, a surprising number of papers and separate 

 works on the fertilisation of all kinds of flowers have ap- 

 peared ; and these are far better done than I could possibly 

 have effected. The merits of poor old Sprengel, so long 

 overlooked, are now fully recognised many years after his 

 death. 



During the same year I published in the Journal of the 

 Linnean Society, a paper On the Two Forms, or Dimorphic 

 Condition of Primula, and during the next five years, five 

 other papers on dimorphic and trimorphic plants. I do not 

 think anything in my scientific life has given me so much 

 satisfaction as making out the meaning of the structure of 

 these plants. I had noticed in 1838 or 1839 the dimorphism 



