CHAP, i.] Joseph G. Koelrentcr and Konrad Sprengel. 419 



tion of its body the anthers in a young flower, and the stigma 

 in an older ; it thus brushes the pollen from the anthers and 

 conveys it to the stigma, and so the pollen of the younger 

 flower fertilises the older.' It has been already said, that 

 Sprengel was also acquainted with the opposite form of dicho- 

 gamy ; and the result of his explanation of both kinds is the 

 conclusion, that some flowers can only be fertilised by the aid 

 of insects, and he adds that some cases are to be found, in 

 which the arrangements in the flower are of such a nature as 

 to involve the injury and even the death of the insect that 

 gives its services. Further on he tells us, that all flowers, 

 ' which are without a proper corolla and have no calyx of any 

 importance in its place, are destitute of nectar, and are not 

 fertilised by insects but by some mechanical means, as by the 

 wind, which either blows the pollen from the anthers on to 

 the stigmas, or shakes the plant or the flower and makes the 

 pollen fall from the anthers on to the stigmas.' He observes, 

 that such flowers always produce a light pollen and in large 

 quantities, whereas the pollen of nectar-bearing plants is heavy. 

 Then he shows how his principles explain all the physiological 

 characters of flowers, position, size, colour, smell, form, time 

 of flowering and the like. 



Sprengel set out with the idea, that the nectar and certain 

 arrangements in flowers are expressly intended for the service 

 of insects; but his investigations led him ultimately to the 

 conclusion, that insects themselves serve not only to effect 

 the fertilisation of plants generally, but also in all ordinary 

 cases to bring about the crossing of different flowers of the 

 same plant or of different plants of the same species. There 

 remained a question, which from Sprengel's strictly teleological 

 point of view especially required an answer, what was the 

 object of this crossing of flowers or individual plants ? Sprang 1 

 was content, as we have seen, with simply stating the fact, and 

 with saying, that nature apparently did not choose that any 

 flower should be fertilised by its own pollen. Who would 



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