PREFACE 



THE SECOND EDITION. 



The first edition of this work was published early in 

 the year 1862, and has been for some time out of print. 

 During the two or three years after its appearance 

 I received, through the kindness of various corre- 

 spondents in different parts of the world, a large 

 uumber of letters, especially from Fritz Miiller in South 

 Brazil, communicating to me many new and curious 

 facts, and calling my attention to some errors. Various 

 memoirs on the fertilisation of orchids have also since 

 been published, and I have myself examined several 

 new and striking forms. A large amount of matter 

 has thus been accumulated; but the present volume 

 would be rendered much too long if the whole were 

 introdiiced. I have, therefore, selected only the more 

 interesting facts, and have given a brief abstract of 

 the several published papers. The work has thus been 

 remodelled ; and the additions and corrections are so 

 numerous that I have found it impossible to follow my 

 usual plan of giving a list of them. I have, however, 



