86 INTRODUCTION 
assemblage of flowers is considerably increased. As Herm. Miiller (‘ Weit. Beob.,’ 
I, p. 299) states, the petals of Ribes sanguineum, which are pure white during 
flowering, become an increasingly darker tint of rose red after the dehiscence 
of the anthers, the pollination of the stigmas, and the cessation of nectar secretion. 
The cunning bees however, which play the part of visitors, confine their attention 
to flowers in which the corolla is still white. In Ribes aureum the petals, at first 
bright yellow, assume a carmine red colour after the stamens and styles fade; thus 
serving the interests of the community, after their own fertilization has been secured, 
by heightening the attractions of the whole. Similar relations are observable (op. 
cit., p. 300) in Weigela rosea, Melampyrum pratense, Aesculus Hippocastanum, 
species of Fuchsia, and others. 
According to Fritz Miiller (Nature, xvii, 1877, p. 79) there occurs in 
Brazil a Lantana with flowers that are red on the first day, orange on the second, 
and purple on the third. 
According to Ludwig (Biol. Centralbl., vi, 1886) there is a remarkable colour- 
change in the flowers of Veronica Sandersoni. The corolla is at first bright red, 
while the filaments and style (about 7 mm. in length) are also red. Later on 
these organs all become white, and the style attains a length of 13 mm. 
The most gorgeous example of colour-change (Ludwig, op. cit.) is that seen in the 
melanostomaceous Pleroma Sellowianum, the flowers of which are at first of a pure 
white, and later on of a purple red. In Spiraea opulifolia (Ludwig, op. cit.) the colour 
continues to change even after fading, becoming most vivid in the ripening capsules. 
In this case, therefore, the fruits as they mature assist in rendering the plant 
conspicuous (Just’s bot. Jahresber., Leipzig, xiv, (1886) 1888, pp. 806, 807). 
Most flowers become inconspicuous as soon as they have been fertilized, 
assuming a dull colour, and either fading or falling off. The state of things 
exemplified by the flowers referred to above, is only possible (Ludwig, op. cit. 
pp- 299, 300) where pollination is effected by a limited set of insects, as otherwise 
fruitless ransacking of the most conspicuous flowers would mean a great waste 
of time, delay fertilization, and undoubtedly in many cases create a distaste in 
the often deceived visitors, so that injury rather than benefit would result. Delpino 
(‘Ult. oss.,’ Atti Soc. ital. sc. nat., Milano, xvi, 1874, p. 28) was the first to give an 
explanation of the colour-change in the flowers of Ribes aureum, suggesting that 
flowers which are over are made conspicuous as such to visitors, which are con- 
sequently spared useless work. According to Herm. Miiller (‘Weit. Beob.,’ I, 
p. 300) such change of colour cannot be the primary significance, for, if it were, 
flowers exhibiting it would not have the least advantage over those that fade or 
fall off immediately after pollination. There can be no doubt that the entire floral 
assemblage is rendered more conspicuous by the persistence and more intense 
coloration of the fertilized flowers, so that insects are attracted in greater numbers. 
But obviously such an adaptation can only be of the greatest use if the fertilized 
flowers are easily to be distinguished from the rest. 
Kerner (‘ Nat. Hist. Pl.’ Eng. Ed. 1, II, pp. 194-5) calls attention to colour- 
contrast between flowers and the ground. In and around woods the surface in 
spring is brown or yellow, owing to the fallen leaves of the previous year. The 
blue flowers of Hepatica triloba contrast admirably with such ground. ‘On ploughed 
