Introductory Sketch. 21 



urchins, to form the sub-kingdom Radiata, because of their radiate 

 structure. Now, in all these creatures we find the system of colour- 

 ation to be radiate also. 



Passing to the old sub-kingdom Articulata, which includes the 

 worms, crabs, lobsters, insects, etc., we come to animals whose 

 structure is segmental ; that is to say, the body is made up of a 

 number of distinct segments. Among these we find the law holds, 

 rigidly that the colouration is segmental also, as may be beautifully 

 seen in lobsters and caterpillars. 



Lastly, we have the Molluscs, which fall for our purpose into two 

 classes, the naked and the shelled. The naked molluscs are often 

 most exquisitely coloured, and the feathery gills that adorn many 

 are suffused with some of the most brilliant colours in nature. 

 The shelled molluscs differ from all other animals, in that the 

 shell is a secretion, almost as distinct from the animals as a house is 

 from its occupant. This shell is built up bit by bit along its margin 

 by means of a peculiar organ known as the mantle —its structure 

 is marginate — its decoration is marginate also. 



We have thus rapidly traversed the animal kingdom, and find 

 that in all cases the system of decoration follows the structural 

 peculiarity of the being decorated. Thus in the : — 



Structureless protozoa there is no varying colouration. 

 Radiate animals — the system is radiate. 

 Segmented „ „ segmental. 



Marginate „ „ marginal. 



Vertebrate „ „ axial. 



We must now expound this great structural law in detail, and we 

 shall find that all the particular ornamentations in their various 

 modifications can be shown to arise from certain principles, 

 namely — 



1. The principle of Emphasis, 



2. The „ Repetition. 



The term Emphasis has been selected to express the marking out 

 or distinguishing of important functional or structural regions by 

 ornament, either as form or colour. It is with colour alone that we 

 have to deal. 



Architects are familiar with the term emphasis, as applied to 

 the ornamentation of buildings. This ornamentation, they say, 

 should emphasize, point out, or make clear to the eye, the use or 



