THE TRIGGER-FISH 



of silica, the other with that of calcareous salts. This 

 quality of building up a skeleton from mineral sub- 

 stances, which we find even in the lowest animals, is 

 continued in others, and finally ends in the pre- 

 dominance of the calcareous salts. 



The minute plankton, among its myriads of tiny 

 living creatures, contains many which possess a 

 skeleton. This is often of such extreme complexity 

 that it is not rivalled even among the highest animals. 

 In the surface waters of all the seas upon the globe 

 are found vast numbers of organisms which compose 

 one class, that of the Ray-animalcules, the largest of 

 which are hardly bigger than the smallest pin's head. 

 Almost all have a siliceous skeleton, the many parts 

 of which are either jointed like armour or else spread 

 out in a series of rods running into the interior of the 

 creature. It is impossible to convey any impression 

 of the delicacy and extraordinary diversity of these 

 tiny rods and the fine plates, whose regular, geometrical 

 construction effects miracles of architecture in these 

 tiny creatures. The finest tracery of a gothic window, 

 the most elaborate pieces of carved ivory from the 

 Far East, are completely outdistanced by these gems 

 of construction brought about simply and solely by 

 the vital activity of an organism which, in every other 

 respect, is so insignificant. The little creature has a 

 very important lesson to teach. It shows us that 

 Nature, not taking into account the stature of her 

 creatures, dispenses her riches to all who owe their 

 existence to her. 



Beginning with these minute beings, and ascending 

 the scale of animal life, we find at every stage different 

 types of supporting apparatus. In the bodies of the 

 sponges there are, according to the species, calcareous 

 rods or siliceous spikelets of many forms, or those 

 elastic filaments which give our household sponges the 

 properties we value. The sea anemones have soft 

 bodies, but their nearest neighbours, the corals, are 

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