AUTHOR'S PREFACE ix 



immense amount of material, I must now and then have overlooked 

 observations on the flower pollination of foreign species. But in such cases 

 these will be found in the third volume. On the other hand, a comparative 

 review has been given in the second volume of Ekstam's accounts of 

 flowers and their guests in Nova Zemlia, the observations of Lindman 

 on floral structure and pollinating agents made in the Dovrefjeld region 

 of the Scandinavian Highlands, the similar researches of Warming with 

 regard both to this region and Greenland, and the works of Aurivillius 

 on insect life in the high North. 



Only the most important of the very numerous descriptions given 

 in Kerner's 'Natural History of Plants' have been referred to in the 

 second volume of this handbook, as most of them are briefly mentioned 

 in Volume I. A complete purview of the very extensive material gathered 

 together in the ' Natural History of Plants ' has not been attempted, as 

 Kerner's work is very widely known. 



In describing the natural orders of plants from the point of view of 

 flower pollination, the indigenous European forms are dealt with at greatest 

 length ; extra-European species are referred to only occasionally, as they 

 are reserved for treatment in the following volume. 



I have endeavoured in this handbook to establish generic characters in 

 flower pollination, as I previously did in my work ' Blumen und Insekten 

 auf den nordfriesischen Inseln ' ; yet this has not been practicable in all 

 cases, for the observations on some species were too imperfect. 



It was not always possible with the resources at my disposal to 

 determine the authors of names of species ; and as reference to the 

 biologist in whose work I found a name did not always furnish the 

 desired information, a few species of plants have had to remain without 

 an author's name. 



Besides observations on insect-visits recorded in works specially de- 

 voted to flower pollination, there are also included records from numerous 

 purely entomological works and treatises, so far as these leave no doubt 

 as to the species of plant concerned^. Among these works are those 

 mentioned in the bibliography (vol. i, p. 212) under the names of the 

 following authors : Alfken, Andre, Aurivillius, Bonnier, Cobelli, v. Dalla 

 Torre, Dours, Ducke, Entleutner, Frey, Frey-Gessner, v. Fricken, Friese, 

 Gerstaecker, Handlirsch, Hofl'er, Holmgren, Koch, Kohl, Krieger, Leege, 

 Marquard, Morawitz, Nylander, P^rez, Redtenbacher, Rossler, Saunders, 

 Schenck, Schletterer, Schiner, Schmiedeknecht, Schultess - Rechberg, 

 Sickmann, Smith, Thomson, and Wiistnei. 



Ambiguous references are neglected, such as : ' Especially in some species of Centaurea and 

 Sedum.' An exception is made, however, in the case of Salix, as experience shows that insects visit 

 the various species indiscriminately. 



