COLOURS OF ANIMALS. 167 



are startled by some gorgeous mass of colour, but as a 

 rule we gaze upon an endless expanse of green foliage, 

 only here and there enlivened by not very conspicuous 

 flowers. Even the orchids, whose superb blossoms 

 adorn our stoves, form no exception to this rule. It is 

 only in favoured spots that we find them in abundance ; 

 the species with small and inconspicuous flowers greatly 

 preponderate ; and the flowering season of each kind 

 being of short duration, they rarely produce any marked 

 effect of colour amid the vast masses of foliage which 

 surround them. An experienced collector in the Eastern 

 tropics once told me, that although a single mountain in 

 Java had produced three hundred species of Orchideae, 

 only about two per cent, of the whole were sufficiently 

 ornamental or showy to be worth sending home as a 

 commercial speculation. The Alpine meadows and rock- 

 slopes, the open plains of the Cape of Good Hope or of 

 Australia, and the flower-prairies of North America, offer 

 an amount and variety of floral colour which can cer- 

 tainly not be surpassed, even if it can be equalled, 

 between the tropics. 



It appears, therefore, that we may dismiss the theory 

 that the development of colour in nature is directly 

 dependent on, and in any way proportioned to the 

 amount of solar heat and light, as entirely unsupported 

 by facts. Strange to say, however, there are some rare 

 and little-known phenomena which prove, that in ex- 

 ceptional cases, light does directly affect the colours of 

 natural objects ; and it will be as well to consider these 

 before passing on to other matters. 



Changes of Colour in Animals produced by Coloured 

 Light. A few years ago Mr. T. W. Wood called attention 



