CHAP, i.] Joseph G. Koelreuter and Konrad SprengeL 421 



direct work of a Creator ; but they had nothing better to put 

 in the place of this idea, and hence Sprengel's discoveries not 

 being understood were neglected till Darwin recognised all 

 their importance, and by opposing the theory of descent and 

 selection to the principle of design was in a position not only 

 to show that they had a scientific meaning, but also to employ 

 them as powerful supports of the theory of selection. Then, 

 too, it became possible rightly to appreciate the contributions 

 of Knight, Herbert, and K. F. Gartner to the further com- 

 pletion of Sprengel's doctrine, for their discoveries also were 

 for a while neglected. A few years after the appearance of 

 Sprengel's book, Andrew Knight 1 relying on the results of 

 experiments made for the purpose of comparing self-fertilisa- 

 tion and crossing in the genus Pisum, laid down the principle, 

 that no plant fertilises itself through an unlimited number of 

 generations; in 1837 Herbert summed up the results of his 

 numerous experiments in fertilisation in the statement, that he 

 was inclined to believe that he attained a better result, when 

 he fertilised the flowers from which he wished to obtain seeds 

 with pollen from another individual of the same variety or at 

 least from another flower, than when he fertilised it with its 

 own pollen ; K. F. Gartner came to the same conclusion after 

 experiments in fertilising Passiflora, Lobelia, and species of 

 Fuchsia in 1844. In these observations lay the first germ of 

 the answer to the question left undecided by Sprengel, why 

 most flowers are so constructed that fertilisation can 'only be 

 fully effected by the crossing of different flowers or of different 

 plants of the same species ; the artificial crossings of this kind, 

 which Knight, Herbert, and Gartner compared with the self- 

 fertilisation of single flowers, showed that crossing procures 

 a more complete and vigorous impregnation than self-fertilisa- 

 tion. It was but a short step from this fact to the idea, that 



1 See Hermann Miiller, ' Befhichtung der Blumen durch Insecten,' Leip- 

 zig (1873), p. 5. 



