BOTANICAL SUBJECTS. 89 



VI.— COLOUR. 



There was a notion that colour was brought into being by the 

 action of light. It is quite true that we cannot see colour in the 

 dark, but it does not follow that it is not therc^ because we cannot 

 see it. 



When one begins to think for himself, he finds that the crimson 

 colour of the nutmeg arillus is crimson, as soon as the pulpy part 

 of the nutmeg is cut open ; the seeds of A brus jnecatorius are of 

 an intense scarlet and black, before the pod bursts ; the grains of 

 the pomegranate are crimson although enclosed in a thick leathery 

 skin ; the claret colour of the blood orange appears the instant the 

 peel is cut open ; the seeds of the Cassia fistula have bright green 

 cotyledons, even when jmripe, and enclosed in a tube of pulp ; so 

 have those of the pistachio-nut, and so on. 



Colour appears to depend on chemical action. Xo doubt it 

 may be intensified and accelerated by light, but it can be brought 

 about quite independently of it, for no one can pretend to say that 

 if you mix solutions of iodide of potassium and bichloride of 

 mercury in the dark, the scarlet iodide of mercury will not result, 

 unless you expose the mixture to the light. 



Mr. J. Berkeley* says that — " The colour of alg£e does not 

 " require much intensity of light for its development. Many 

 " species of beautiful colours grow at depths, where the light must 

 " be so small that no phoenogam could exhibit anything of its 

 " proper hue, supposing it possible for its blossoms to be developed 

 " under such conditions." 



Gems and other minerals have their brilliant colours at what- 

 ever depth they may be ; and we do see that phcenogams, such as 

 the carrot and beetroot, develop their orange and crimson colours 

 in what we would consider as total darkness. 



* lutrod. to " CryptofTamie Botany," p. 97. 



