Fertilisation of Orchids 405 



beyond the initial stage, we cannot be surprised that other botanists 

 followed to even a less extent the lines laid down by Kblreuter and 

 Sprengel. This was in part the result of Sprengel's supernatural 

 teleology and in part due to the fact that his book appeared at a 

 time when other lines of inquiry exerted a dominating influence. 



At the hands of Linnaeus systematic botany reached a vigorous 

 development, and at the beginning of the nineteenth century the 

 anatomy and physiology of plants grew from small beginnings to a 

 flourishing branch of science. Those who concerned themselves with 

 flowers endeavoured to investigate their development and structure 

 or the most minute phenomena connected with fertilisation and the 

 formation of the embryo. No room was left for the extension of the 

 biology of flowers on the lines marked out by Kblreuter and Sprengel. 

 Darwin was the first to give new life and a deeper significance to 

 this subject, chiefly because he took as his starting-point the above- 

 mentioned problems, the importance of which is at once admitted by 

 all naturalists. 



The further development of floral biology by Darwin is in the 

 first place closely connected with the book on the fertilisation of 

 Orchids. It is noteworthy that the title includes the sentence, — 

 "and on the good effects of intercrossing." 



The purpose of the book is clearly stated in the introduction : — 

 " The object of the following work is to show that the contrivances 

 by which Orchids are fertilised, are as varied and almost as perfect 

 as any of the most beautiful adaptations in the animal kingdom ; 

 and, secondly, to show that these contrivances have for their main 

 object the fertilisation of each flower by the pollen of another 

 flower 1 ." Orchids constituted a particularly suitable family for 

 such researches. Their flowers exhibit a striking wealth of forms ; 

 the question, therefore, whether the great variety in floral structure 

 bears any relation to fertilisation 2 must in this case possess special 

 interest. 



Darwin succeeded in showing that in most of the orchids examined 

 self-fertilisation is either an impossibility, or, under natural condi- 

 tions, occurs only exceptionally. On the other hand these plants 

 present a series of extraordinarily beautiful and remarkable adapta- 

 tions which ensure the transference of pollen by insects from one flower 

 to another. It is impossible to describe adequately in a few words 

 the wealth of facts contained in the Orchid book. A few examples 

 may, however, be quoted in illustration of the delicacy of the obser- 

 vations and of the perspicuity employed in interpretating the facts. 



1 Fertilisation of Orchids, p. 1. 



2 In the older botanical literature the word fertilisation is usually employed in cases 

 where ^pollination is really in question : as Darwin used it in this sense it is so used here. 



