AUTHOR’S PREFACE vii 
works in Italian and French. I have, therefore, frequently been obliged to 
content myself with information derived from references in the ‘ Botanischer 
Jahresbericht’ (1883 to 1895), and the ‘Botanisches Centralblatt.’ Some 
works had to be left altogether unnoticed, as I was not able to get any 
information as to their contents. A few have no doubt escaped me 
altogether, but I hope to have attained at least relative completeness. 
In course of the preparation of the material, it appeared that the 
work would be too comprehensive for a single volume. I determined, 
therefore, to publish in the following divisions.— 
1. Introduction and Literature. 
2. The Observations in Flower Pollination hitherto made in Europe 
and in the Arctic regions. | 
(2) Ranunculaceae to Compositae. 
(4) Lobeliaceae to Coniferae. 
3. Observations in Flower Pollination made outside Europe. 
In the introduction, I have given, in the first place, a short survey 
of the historical development of flower pollination. In doing this I was 
chiefly concerned with introducing the most prominent facts in this 
sphere of research, especially the labours of Kolreuter and Sprengel, and 
the development of the floral theory which is associated with the names 
of Sprengel, Knight, Darwin, Hildebrand, Axell, Delpino, and Hermann 
Miller. This short survey will sufficiently elucidate the present stand- 
point of flower pollination. I was freed from the necessity of exhaustively 
considering the historical development of this science by the excellent 
work of E. Loew, ‘Einfiihrung in die Bliitenbiologie auf historischer 
Grundlage’ (Berlin, 1895). In this work the subject is treated at great 
length, and accordingly Loew’s ‘Introduction’ forms a necessary sup- 
plement to my handbook. 
In the second division of the introduction, besides my own writings 
and those of Hermann Miiller, I have made most use of the works of 
Charles Darwin, F. Delpino, W. O. Focke, F. Hildebrand, A. Kerner, 
O. Kirchner, E. Loew, F. Ludwig, H. von Mohl, Fritz Miiller, Christian 
K. Sprengel, Aug. Schulz, and E. Warming ; and from these an idea of 
the present position of flower pollination is obtained. The lists of self- 
sterile, self-fertile, and cleistogamous flowers may not, however, be quite 
complete. 
The compilation of the literature of flower pollination was made much 
easier by the following: ‘ Bibliography’ in D’Arcy W. Thompson’s transla- 
tion of Hermann Miiller’s ‘Befruchtung der Blumen durch Insekten’ 
(‘ The Fertilisation of Flowers,’ London, 1883, pp. 599-630), which contains 
most references to literature up to the year 1882; MacLeod’s ‘ Lijst van 
