vi AUTHOR’S PREFACE 
in trying to clear up such contradictions by my own investigations, and 
in endeavouring by my own research to increase our knowledge of floral 
adaptations, and of the visitors to our flowers, so that this book will 
seldom be consulted in vain by any one who desires information of 
this sort with regard to our indigenous or cultivated plants. 
It would, however, have been impossible for me to bring the work to 
a conclusion in the comparatively short space of three years, if I had 
not been able to make use of several excellent recent works on Flower 
Pollination, especially those of Kerner, Loew, and Ludwig, and unless I had 
been given most friendly assistance by numerous flower specialists, and by 
my other botanical and entomological friends, who were always ready to 
help me in every possible way. I therefore take this opportunity of 
renewing my thanks to all these, especially to the following gentlemen :— 
D. ALFKEN in Bremen, O. APPEL in Wiirzburg, J. BEHRENS in Karlsruhe, 
F. BUCHENAU in Bremen, J. HENRY BURKILL in Kew, C. CORRENS in 
Tiibingen, F. DAHL in Berlin, K. v. DALLA TorRE in Innsbruck, F. DELPINO 
in Naples, O. EkSTAM in Troms6, TH. FRIES in Upsala, A. GLOY in 
Kiel, A. HANSGIRG in Prague, J. H. HART in Port of Spain (Trinidad), 
F. HILDEBRAND in Freiburg i. B.. A. KERNER VON MARILAUN in Vienna, 
O. KIRCHNER in Hohenheim, A. KNEUCKER in Karlsruhe, E. LOEW in 
Berlin, F. LUDWIG in Greiz, J. MACLEOD in Ghent, P. MAGNUS in Berlin, 
TH. MEEHAN in Germantown, Philad.(U.S.A.), F. MULLER (f) in Blumenau 
(Brazil), G. NATHORST in Stockholm, F. PLATEAU in Ghent, K. RECHINGER 
in Vienna, CH. ROBERTSON in Carlinville, Ill. (U.S. A.), CHR. SCHRODER 
in Itzehoe, A. SCHULZ in Halle, G. F. SCOTT-ELLIOT in Glasgow, 
P. STOLZENBURG in Kiel, J. URBAN in Berlin, C. VERHOEFF in Bonn, 
E. WARMING in Copenhagen, and C. WARNSTORF in Neu-Ruppin. I also 
carried on at times a very extensive correspondence on the subject of 
this book, especially with Herren ALFKEN, APPEL, KIRCHNER, LOEW, 
and LUDWIG. 
It was my intention to embellish this work with portraits and auto- 
graphs of all the most distinguished specialists in flower pollination, but it was 
impossible to obtain photographs of all. I have, therefore, confined myself 
to giving portraits of those to whom we are indebted in the highest degree 
for the advancement of the subject: i.e. J. G. Kdlreuter, Charles Darwin, 
H. and F. Miiller, F. Delpino, F. Hildebrand, and S. Axell. Unfortunately 
no portrait of the grand master of our science, Christian K. Sprengel, was 
to be had. There is given, therefore, in the absence of this, a reduced fac- 
simile of the characteristic title-page of his book ‘ Das entdeckte Geheimnis.’ 
I have endeavoured, so far as possible, to make use of the original 
memoirs of authors in recounting their observations, and have also, when 
practicable, adhered to the terms used by them, but I was not able to see 
all the original works on Flower Pollination, in particular the more recent 
