6 INTRODUCTORY REMARKS. CHAP. I 



and Hermann Miiller,* and numerous shorter papers, 

 Have been published. A list would occupy several 

 pages, and this is not the proper place to give their 

 titles, as we are not here concerned with the means, 

 but with the results of cross-fertilisation. No one 

 who feels interest in the mechanism by which nature 

 effects her ends, can read these books and memoirs 

 without the most lively interest. 



From my own observations on plants, guided to a 

 certain extent by the experience of the breeders of 

 animals, I became convinced many years ago that it 

 is a general law of nature that flowers are adapted to 

 be crossed, at least occasionally, by pollen from a 

 distinct plant. Sprengel at times foresaw this law, but 

 only partially, for it does not appear that he was aware 

 that there was any difference in power between pollen 

 from the same plant and from a distinct plant. In the 

 introduction to his book (p. 4) he says, as the sexes 

 are separated in so many flowers, and as so many other 

 flowers are dichogamous, " it appears that nature has 

 not willed that any one flower should be fertilised by 

 its own pollen." Nevertheless, he was far from keeping 

 this conclusion always before his mind, or he did not 



* Sir John Lubbock has given known, visit the flowers of each 



an interesting summary of the species. He likewise enters on 



whole subject in his ' British Wild new ground, by showing not only 



Flowers considered in relation to that flowers are adapted for their 



Insects,' 1875. Hermann Miiller's own good to the visits of certain 



work ' Die Befruchtung der Blu- insects ; but that the insects 



men durch Insekten,' 1873, con- themselves are excellently adapted 



tains an immense number of for procuring nectar or pollen 



original observations and gene- from certain flowers. The value 



ralieations. It is, moreover, in- of H. Miiller's work can hardly be 



valuable as a repertory with re- over-estimated, and it is much to 



ferences to almost everything be desired that it should be trans- 



which has been published on the kted into English. Severin 



subject. His work differs from Axell's work is written in Swedish, 



that of all others in specifying so that I have not been able to 



what kinds of insects, as far as read it. 



