THE POLLINATION OP PPAR PLOWERS; 



GHAPTEK I. 

 PRELIMINARY REMARKS ON CROSS-POLLINATION. 



The question of eross-polliiiatiou of flowers dates back to the pub- 

 lication of Darwin's Origin of Sx)ecies in 1859, in which the value of a 

 cross, or at least of the advantage of an occasional cross, was first 

 jioiuted out. However, no general interest in the subject was aroused 

 until 1862, when this great investigator published his work on Various 

 Contrivances by which British and Foreign Orchids are Fertilized by 

 Insects. The most important conclusion in this book is found in the 

 following sentence : ''N^ature thus tells us in the most emx^hatic manner 

 that she abhors perpetual self-fertilization." 



Long before Darwin's time Sprengel published a remarkable book,t 

 in which he showed by a great number of observations the essential 

 part insects play in pollinating flowers. He even went so far as to 

 actually observe in certain species of plants that cross-i)ollination neces- 

 sarily took place, but not comprehending the advantage of this to the 

 plauts he did not fully appreciate the importance of his discoveries. 

 Andrew Knight | saw the truth much more clearly, and remarked that 

 nature intended that sexual intercourse should take place between 

 neighboring i)lants of the same species. In 1811 Kolreuter and later on 

 Herbert also hinted at the same law, but Sprengel's important observa- 

 tions remained unappreciated until Darwin's great discoveries of the 

 value of crossing to plants showed the real meaning and utility of all 

 the contrivances which brought it about. In his remarkable work on 

 Cross and Self-Fertilization in the Vegetable Kingdom, Darwin has 

 brought forward his own exhaustive experiments showing the value of 



* Tliroughout this report an endeavor lias been made to avoid the use of the word 

 fertilization and to substitute pollination when the application of the pollen to the 

 pistil is meant, and fecundation to mean the action of the pollen tube on the ovules. 

 The word fertilization, however, is used in addition by various authors in a general 

 sense to cover both pollination and fecundation, and when so used it is not so easj^ 

 to substitute either of the other words. Moreover, in quotations and citations of 

 book titles the word fertilization must be used, so altogether it occurs in a number of 

 places. 



t Sprengel. Ch. K. Das entdeckte Gelieimniss der Natur im Ban und in dcr 

 Befruchtung dor Blnmeu, Berlin, 1798. 



t Darwin's Cross and Self-Fertilization in the Vegetable Kingdom, p. 7. 



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