X AUTHOR'S PREFACE 



Some of these works, for instance those of Alfken, Dalla Torre, Frey, 

 Friese, Hoffer, Krieger, Morawitz, Schletterer, and Sickmann, contain in 

 places an amazing amount of material for use by the flower specialist, 

 and frequently afford the only available information as to visitors to 

 flowers. Others, on the contrary, as, for instance, Andre's work, which 

 is in many volumes, contain only a few useful notices. There are numerous 

 other entomological works, especially in French and Italian, which might 

 have been referred to, but to have done so would have greatly increased 

 the toil of compilation ; and it is questionable if the result would have 

 repaid the labour. Some, indeed, of the works that were looked into 

 contained no useful information at all, as, for instance, Aurivillius (Gronlands 

 insektfauna ; Vet.-Ak. Bih., Stockholm, Vol. xv, Ser. 4, Nr. i, pp. 1-33) 

 and F. Chevrier (Description des Chrysides du Bassin du L^man, Geneva, 

 1862)^ 



Herr D. Alfken has placed at my disposal his valuable observations 

 on the visits of insects to flowers in the neighbourhood of Bremen. Some 

 observations of Hans Hoppner, that also refer to the neighbourhood of 

 Bremen, are added. Further, Herr Alfken has communicated to me, in 

 addition to his previously published observations on the Island of Juist, 

 a number of new ones. 



Besides my own obsei^vations on the visits of insects to flowers, and 

 in addition to those of Borgstette, Buddeberg, Burkill, Cobelli, Darwin, 

 Delpino, Ekstam, Heinsius, Lindman, Loew, MacLeod, Hermann Miiller, 

 Plateau, Rathay, Ricca, Schneider, A. Schulz, Scott-Elliot, Sprengel, 

 Verhoeff, de Vries, Willis, and Wittrock, there is a very considerable mass 

 of work containing material useful in studying flower pollination ; 

 so that here again only a relative independence can be claimed. The 

 ' tedious ' lists of visitors, in which thousands of individual observations 

 are set down, form the indispensably necessary statistical material upon 

 which to base our knowledge of the relations subsisting between groups 

 of flowers and insects. They afford an insight into the connection between 

 the structure of flowers and the anatomical characters of insects ; they tell 

 us that everywhere flowers are sought out in preponderating majority by 

 such insects as are modified in adaptation to them. I reserve this statistical 

 material for working up afresh. 



It must be admitted that in the enumeration of visitors, the record 



* There were also no observations on flower pollination in works that I looked through by 

 M. J. Perez (Contribntions i la faune des Apiaires de France, 11° partie, Parasites. — Actes soc. 

 linn. Bordeaux, 1883) and by Ruggero Cobelli (Gli imenotteri di Trentino, Fasc. I: Fonnicidae, 

 Rovereto, 1887 ; Fasc. II: Tenthredinidae, Apidae, Chrysididae, Pompilidae, Scoliadae, Mutillidae, 

 Sapygidae, 1891 ; Fasc. Ill : Vespidae. — Sphegidae, 1893 ; Fasc. IV: Evanidae, Cynipidae, Chal- 

 cididae, Proctotrupidae, Ichneumonidae, Braconidae, 1897). 



