XXXI 
IVORY 
From time immemorial certain natural productions 
in the mineral and animal world have been highly 
esteemed for artistic and decorative purposes. Among 
such substances gold, silver, marble, precious stones, 
and ivory have held leading places. 
Among these materials ivory holds a peculiar 
position, inasmuch as it is the most durable substance 
furnished by the animal kingdom. Moreover, ivory, like 
gold, silver, and diamonds, cannot be made artificially, 
and no satisfactory substitute has been devised to 
supply its place in the various arts and industries of the 
civilised world. 
Ivory is known to anatomists as dentine and it 
enters into the formation of the teeth of mammals, but 
the term ivory is restricted by use to the dentine of 
those animals in which it occurs in sufficient quantity 
to be useful for industrial and artistic purposes. Such 
mammals are the elephant, hippopotamus, narwhal, 
sperm-whale, and walrus. 
The chief source of the best ivory to-day is the 
tusks of the African elephant. The tusks are the 
permanent upper incisors of this huge mammal; they 
not only surpass other teeth as belonging to an animal 
so enormous, but they are the largest of all teeth in 
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