ch. xvi.] FERTILISATION OF FLOWERS. 329 



If we examine the literature relating to the fertilisation 

 of flowers, we do not find that this new branch of study 

 showed any great activity immediately after the publication 

 of the Orchid-book. There a few papers by Asa Gray, in 

 1862 and 1863, by Hildebrand in 1864, and by Moggridge 

 in 1865, but the great mass of work by Axell, Delpino, 

 Hildebrand, and the Miillers, did not begin to appear until 

 about 1867. The period during which the new views were 

 being assimilated, and before they became thoroughly fruit- 

 ful, was, however, surprisingly short. The later activity in 

 this department may be roughly gauged by the fact that 

 the valuable * Bibliography,' given by Professor D'Arcy 

 Thompson in his translation of Muller's Befruchtung 

 (1883),* contains references to 814 papers. 



In 1877 a second edition of the Fertilisation of Orchids 

 was published, the first edition having been for some time 

 out of print. The new edition was remodelled and almost 

 rewritten, and a large amount of new matter added, much 

 of which the author owed to his friend Fritz Muller. 



With regard to this edition he wrote to Dr. Gray : 



" I do not suppose I shall ever again touch the book. 

 After much doubt I have resolved to act in this way with 

 all my books for the future ; that is to correct them once 

 and never touch them again, so as to use the small quantity 

 of work left in me for new matter." 



One of the latest references to his Orchid-work occurs in 

 a letter to Mr. Bentham, February 16, 1880. It shows the 

 amount of pleasure which this subject gave to my father, 

 and (what is characteristic of him) that his reminiscence of 

 the work was one of delight in the observations which pre- 

 ceded its publication, not to the applause which followed it : 



" They are wonderful creatures, these Orchids, and I 

 sometimes think with a glow of pleasure, when I remember 

 making out some little point in their method of fertilisa- 

 tion." 



The Effect of Cross- and Self-fertilisation in the Vegetable 

 Kingdom. Different Forms of Flowers on Plants of 

 the same Safeties. 



Two other books bearing on the problem of sex in 

 plants require a brief notice. The Effects of Cross- and 



* My father's " Prefatory Notice " to this work is dated February 6th, 

 1882, and is therefore almost the last of his writings. 



