Mr Tylor Quoted 
more rapidly than that which forms at another ; 
this, of course, will result in a preponderance in 
the organism of the colour which is produced at 
the former centre. 
Further, we must bear in mind that the develop- 
ment of each colour-producing unit is largely 
affected by conditions external to it, as we shall 
see when dealing with Sexual Dimorphism. 
More than one naturalist, who has paid careful 
attention to the subject of animal colouration, has 
perceived that through the apparently endless 
diversity of the colouring of organisms something 
like order runs. 
Over thirty years ago Mr Alfred Tylor called 
attention to this important fact. That observer, 
whose views met with the approval of Wallace, 
was of opinion that colour follows structure, and 
that in a many-hued animal it changes at points 
where the function changes. 
“Tf,” writes Mr Tylor, “we take highly 
decorated species—that is, animals marked by 
alternate dark or light bands or spots, such as 
the zebra, some deer, or the carnivora, we find, 
first, that the region of the spinal column is 
marked by a dark stripe; secondly, that the 
regions of the appendages, or limbs, are differ- 
ently marked ; thirdly, that the flanks are striped 
or spotted, along or between the regions of the 
lines of the ribs; fourthly, that the shoulder and 
hip regions are marked by curved lines ; fifthly, 
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