204 SUPPLEMENT TO THE INTRODUCTION 
Owing to the disaffection of the gardeners placed under him, it became im- 
possible for K6lreuter to retain his offices. He continued his experiments on 
hybridization in his private garden up to 1776. He then took a house which had 
no garden connected with it, so that he ceased to have opportunity for making 
such experiments. He died on November 11, 1806. A list of his other botanical 
works is given in the Bibliography of Flower Pollination. 
2. How Flowers attract Insects. 
While volume I of this handbook of Flower Pollination was in the press there 
appeared five parts of a treatise by Félix Plateau entitled ‘Comment les fleurs 
attirent les insectes. Recherches expérimentales’ (i.e. How Plants attract Insects. 
Experimental Investigations)’. These may well attract our serious attention, for the 
conclusions which Plateau draws from his experiments are such as to shake belief in 
a view that has hitherto prevailed as a fundamental oecological law. As already 
stated in a preliminary communication made to the ‘ Naturwissenschaftlicher Verein 
fiir Schleswig-Holstein’ (Schleswig-Holstein Society of Natural Science) on Feb. 14, 
1898, and in a paper in the ‘ Botanisches Centralblatt’ (Ixxiv, 1898, pp. 39-46), 
I do not agree with Plateau’s conclusions, but interpret his experiments in an 
essentially different way. 
The first communication by Plateau on this subject is known to me only from 
reviews. The author wrote me that he had no spare copy to give because too few 
reprints of the paper had been struck off, and his supply of them was exhausted. 
According to the review by Kienitz-Gerloff in the ‘ Botanische Zeitung’ of April 16, 
1896 (Ixvi, pp. 123 and 124), Plateau limited himself almost entirely in the first 
part of his treatise to the results of investigations he had carried out on dahlia 
flowers which were not in full bloom. He covered in some instances only the ray- 
florets, in others both ray- and disk-florets, partially or completely with papers of 
various colours, or with leaves of the same green as those of the dahlias. From 
the number of insect visits made to the flowers—by species of Bombus, Megachile, 
Pieris, and Vanessa—during the space of an hour, Plateau arrived at the following 
preliminary conclusions with regard to ligulate Compositae—conclusions which are 
repeated in the second part of his memoir :— 
1. Insects actively visit unmutilated inflorescences when the form and colour of 
the florets are masked by green leaves. 
2. The form and bright colours of the capitula do not appear to exercise an 
attractive influence. 
3. The coloured ray-florets of single dahlias—and consequently of other ligulate 
Compositae—do not play the part of a flag or signal as has hitherto been 
supposed. 
4. The forms and colours of flowers do not appear to serve as means of attraction, 
but insects are apparently guided to the capitula of Compositae by some sense 
other than sight, probably by smell. 
! Bull. Acad. roy., Bruxelles, Series 3, xxx, 1895, pp. 466-88 ; xxxii, 1896, pp. 505-34; Xxxiii, 
1897, pp. 17-41 ; xxxiv, 1897, pp. 601-44 and pp. 847-81. 
