404- Dr. Dickie on Associations of Colour and Relations 



In most Orchidese we find constant associations of yellow and 

 purple. 



We need not expect to find in a corolla or any other organ 

 pure red and pure yellow, or blue and red, in contact with each 

 other. 



Of the primaries, blue is the least common, and in fact, gene- 

 rally speaking, may be called very rare ; many so-called blues 

 being blue-purples : transmitted light shows this. Pure blue 

 being so uncommon in any organism, Professor M'Cosh sug- 

 gested to me that this is compensated for in the atmosphere, and 

 I may add, in the ocean too. Yellow is probably the most 

 general of the primaries, in the flower at least ; the most com- 

 mon association is therefore yellow and purple. We can now 

 understand why yellow is the usual colour of the pollen, and 

 some exceptional cases seem to confirm this ; in the Turn-cap 

 Lily for instance, the decidedly red pollen is associated with the 

 green filaments of the anthers. 



The statistics of colour in different natural orders have not been 

 fully examined ; it may be remarked, however, that purple and 

 citrine prevail in the flowers of the Glasses, and russet and dark 

 green in the Junci. In the Fir-tribe and its allies, secondaries 

 and tertiaries are common, such as the purple and citrine scales 

 of young and old cones, the russet and dark green in the stems 

 and leaves respectively ; at the same time the copious yellow 

 pollen must not be lost sight of. 



In examining this subject, we must keep in view that the 

 colour of the flower may have its complement in that of other 

 organs, as stem, leaf, &c. It sometimes happens that one of the 

 associated colours is not visible to the eye at all times. The 

 inside of a nearly ripe fig is red-purple, the outside yellow-green ; 

 the same is true of the pericarp in some species of Preony. In 

 some Cactacese the yellow corolla is succeeded by a purple fruit. 



The newly ripened cone of the Pinus Pinaster is citrine ; when 

 the scales open, the complementary purple is revealed at the base 

 of each. In the fruit, fixed relations of colour are probably too 

 familiar to require illustration. In certain varieties of the Apple, 

 red and red-purple, green and yellow-green of various hues and 

 shades are associated. In some varieties of Pear, yellow-green, 

 red-purple and citrine occur together. 



Direct exposure to light, although usually, and in general 

 correctly admitted to have a direct relation to intensity of colour 

 in organisms, appears not to be necessary in every instance ; the 

 plant, however, must receive the light at some part or other in 

 order to produce that depth of colour observed in the coats of 

 seeds, the interior of fruits, and in the tissues of subterranean 

 organs . 



