COLOURS OF FLOWERS AS A MEANS OF ATTRACTING ANIMALS. 197 



"Queen of the Night" (Cereus nycticalus) is shown in Plate VII. opposite p. 641, 

 vol. i. When dai'k-coloured flowers are visited at night by insects, for example, 

 those of Hesperis tristis, Pelargonium triste and atrum, it is not in consequence 

 of the colour but of the scent of the flowers, as will be described later on. Without 

 doubt, white is the colour which is not only best seen in the dark, but can be plainly 

 distinguished in bright daylight, and it is, as far as we know, not avoided by a 

 single flower-visiting animal. Even those animals which have a badly-developed 

 sense of colour, and can perhaps only distinguish between light and dark, are able 

 to appreciate white, as it is the lightest of all colours. Yellow flowers are eagerly 

 visited by animals which collect and eat pollen, perhaps because the pollen is usually 

 coloured yellow. Greenish-yellow and brownish-yellow flowers, as, for example, 

 those of the Parsley and the Parsnip, of the Aralia and the Ivy, of the Maple and 

 the Buckthorn, of the Rue and the Sumach (PetroselinuTn, Pastinaca, Aralia, Hedera, 

 Acer, Rhamnus, Ruta, Rhus), are especially preferred by flies which swarm over 

 dungheaps and other refuse (e.g. Lucilia cornicina, Onesia sepulcralis, Sarcophaga 

 carnaria, Scatophaga stercoraria). This phenomenon has been explained by the 

 similarity of the colours named with those of the dungheap and ofl'al generally. 

 Dark brown must exercise a specially attractive power over wasps. They fly with 

 great haste to brown flowers, especially those whose tint resembles that of decaying 

 pears and other fruit, whilst they will pass by colours which are far more noticeable 

 to other eyes. Flowers of a pale, fawn-red, and dirty violet colour in conjunction 

 with brown, so arranged as to resemble decaying flesh and dead bodies, and such 

 flowers as possess by way of additional attraction a smell of putrefaction, are always 

 visited by carrion-flies and dung-beetles in abundance. It might be thought that 

 the smell alone would sufiice to attract these insects; but it must be otherwise, or 

 it is diflicult to see why the various Aristolochias, Stapelias, Rafflesias, and Balano- 

 phoreiB, which smell like carrion, should bear its colours as well as its scent. It is 

 not easy to decide how much depends upon the colouring, and how much on the 

 scent, and it would be premature to give a definite judgment now. It should be 

 noted generally that the opinions just stated should not be accepted as being entirely 

 free from doubt. Researches on these points are very difiScult, and there are so 

 many sources of error that the results may have to undergo many corrections sooner 

 or later. But, on the other hand, all that has been said must not be regarded as 

 quite worthless. This one thing is quite certain — that some animals will show a 

 preference for one colour in a flower, while others will prefer another, and that the 

 absence or presence, the significance or prominence of single floral colours is to be 

 placed on a parallel with the same phenomena in the Animal Kingdom. 



It is extremely probable also that in many floral regions the predominance of 

 certain floral colours at various seasons of the year is connected with the distribution 

 of animals in time, since the insects which fly about in spring and summer, and in 

 summer and autumn diflTer from one another. It has been shown graphically by 

 curves for the region of the Baltic flora that in April and May a white colour 

 predominates, and that from the highest point in May the curve of white gradually 



