SEVENTEENTH AND EIGHTEENTH CENTURIES 157 

 tected from the rain, and further that they are often characterized by special 

 colours, whence he concludes that their object must be to attract insects 

 to the flowers; but then the insects must themselves have some object in 

 their visits, and this he found, as did Koelreuter before him, to be the 

 conveyance of pollen from stamen to pistil. He now studied in detail the 

 relation of the insects to the flowers and noticed that certain flowers are in- 

 variably fertilized by special insect forms, others again by several different 

 forms, and that the position of the nectaries in each flower is adapted not 

 only to the flower's general conditions of life, but also to the insects that 

 visit it. Further, he discovered that in a number of bisexual flowers stamen 

 and pistil actually develop during different periods, and that therefore the 

 flower cannot be fertilized by its own pollen, but that pollen is conveyed 

 by the insects from flower to flower. This fact he calls dichogamy, a name 

 which is still used, and he concludes from it that "Nature does not appear 

 to desire that a flower be fertilized by its own pollen." Finally, he explains 

 more lucidly than any of his predecessors the contrast between flowers fer- 

 tilized by insects and those fertilized by the wind; on this subject, too, he 

 makes many striking observations. 



Space forbids a more detailed account of the numerous shrewd and far- 

 reaching observations which Sprengel adduces in support of his theories. 

 Through his work he has laid a lasting foundation for one of the most 

 important sections of vegetable biology, and besides, in regard to insect 

 research, he has pointed out a method of far greater theoretical importance 

 than mere classification and collecting. And so the utter lack of understand- 

 ing shown for his work by his own age was all the more tragic. The natural 

 philosophers of the Romantic Age deeply despised detailed research work of 

 this kind, and the succeeding generation, which endeavoured to revive the 

 mechanistic conception of nature of the eighteenth century, felt embarrassed 

 by the detailed finality which Sprengel sought and found in the structure 

 and life of the flowers. It was only Darwin's authority that succeeded in 

 rescuing Sprengel from oblivion; in the flowers' and insects' mutual depend- 

 ence upon one another he found support for his theory of selection and 

 himself carried out investigations in this field, which will be described in 

 a later chapter. Thus Sprengel found redress — tardy but glorious. 



