220 THE OCEAN WORLD. 
of the polyps. The tissue of these singular beings is of an intensely 
red colour. The disposition of their tubes in the style of organ pipes 
has always attracted the attention of the curious inquirer into the 
secrets of Nature. 
Fig. 78.—The Sea Fan, Gorgonia flabellum (Linn). 
II. GORGONID. 
Milne-Edwards divides this order into three natural groups :— 
I. The Gorgonine. II. The Jsidine. III. The Coralline. 
The Gorgonine are composed of two substances : the one external, 
sometimes gelatinous ; sometimes, on the contrary, cretaceous, fleshy, 
and more or less tenacious. Animated with life, this membrane is 
irritable, and encloses the polyp ; it becomes friable, and often peels 
off like bark in drying. The second substance, internal and central, 
