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 Kolreuter 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 Kélreuter 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’.’ 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? 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. : 
4 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, 
