158 CHARLES DARWIN 



tion tends in the long run to degradation, degeneration, 

 and final extinction. 



Here as elsewhere, however, Darwin's principle does 

 not spring spontaneous, like Athene from the head of 

 Zeus, a goddess full-formed, uncaused, inexplicable : it 

 aiises gradually by a slow process of development and 

 modification from the previous investigations of earlier 

 biologists. At the close of the last century, in the 

 terrible year of upheaval 1793, a quiet German botanist, 

 Christian Konrad Sprengel by name, published at 

 Berlin his long unheeded but intensely interesting work 

 on the 'Fertilisation of 'Flowers.' In the summer of 

 1789, while all Europe was ablaze with the news that 

 the Bastile had been stormed, and a new era of humanity 

 begun, the Calm and peaceful Pomeranian observer was 

 noting in his own garden the curious fact that many 

 flowers are incapable of being fertilised without the 

 assistance of flying insects, which carry pollen from the 

 stamens of one blossom to the sensitive surface or 

 ovary of the next. Hence he concluded that the secre- 

 tion of honey or nectar in flowers, the contrivances by 

 which it is protected from rain, the bright hues or lines 

 of the corolla, and the sweet perfume distilled by the 

 blossoms, are all so many cunning devices of nature 

 to ensure fertilisation by the insect-visitors. Moreover, 

 Sprengel observed that many flowers are of one sex only, 

 and that in several others the sexes do not mature 

 simultaneously ; ' so that,' said he, ' nature seems to 

 intend that no flower shall be fertilised by means of its 

 own pollen.' Indeed, in some instances, as he showed 

 by experiments upon the yellow day lily, plants impreg- 

 nated from their own stamens cannot be made to set 



