204 SUPPLEMENT TO THE INTRODUCTION 



Owing to the disaffection of the gardeners placed under him, it became im- 

 possible for Kolreuter 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 Felix Plateau entitled ' Comment les fleurs 

 attirent les insectes. Recherches exp^rimentales ' (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-Si. 



