xi] OF EVOLUTION 141 



and he was called upon immediately to prepare a 

 second edition, we find that on January 1st, 1860, 

 Darwin began to arrange his materials for dealing with 

 the first great division of his subject, 'the variation 

 of animals and plants under domestication/ So 

 numerous and important were his notes and records 

 of experiments, however, that he soon found that to 

 expand the whole of the ' abstract,' on the same scale, 

 would be an impossible task for any one man, however 

 able and diligent. Unwilling that the results of 

 some of his special researches should be lost, he 

 wisely determined to issue them as separate books. 

 The first of these to appear was that on the Fer- 

 tilisation of Orchids, a beautiful illustration of the 

 relation of insects to flowers in producing crossing. 

 He had been more than twenty years working and 

 experimenting on this subject, his interest in it having 

 been quickened by having read an almost forgotten 

 book of the botanist Sprengel. Almost at the same 

 time, and in following years, he wrote papers for the 

 Linnean Society on dimorphic and trimorphic forms 

 of flowers, and their bearing on the question of cross- 

 fertilisation. These papers were the foundation of 

 his well-known work, The Different Forms of Flowers 

 on Plants of the same Species. In the same way, 

 a paper read in 1864 to the Linnean Society was 

 subsequently expanded into The Movements and 

 Habits of Climbing Plants. 



