138 CREATIVE EVOLUTION CHAP. 



more species became mobile, the more they became 

 voracious and dangerous to one another. Hence a 

 sudden arrest of the entire animal world in its pro 

 gress towards higher and higher mobility ; for the 

 hard and calcareous skin of the echinoderm, the shell 

 of the mollusc, the carapace of the crustacean and the 

 ganoid breast-plate of the ancient fishes probably 

 all originated in a common effort of the animal species 

 to protect themselves against hostile species. But this 

 breast-plate, behind which the animal took shelter, 

 constrained it in its movements and sometimes fixed 

 it in one place. If the vegetable renounced con 

 sciousness in wrapping itself in a cellulose membrane, 

 the animal that shut itself up in a citadel or in armour 

 condemned itself to a partial slumber. In this torpor 

 the echinoderms and even the molluscs live to-day. 

 Probably arthropods and vertebrates were threatened 

 with it too. They escaped, however, and to this 

 fortunate circumstance is due the expansion of the 

 highest forms of life. 



In two directions, in fact, we see the impulse of life 

 to movement getting the upper hand again. The 

 fishes exchanged their ganoid breast-plate for scales. 

 Long before that, the insects had appeared, also dis 

 encumbered of the breast-plate that had protected their 

 ancestors. Both supplemented the insufficiency of their 

 protective covering by an agility that enabled them to 

 escape their enemies, and also to assume the offensive, 

 to choose the place and the moment of encounter. We 

 see a progress of the same kind in the evolution of 

 human armaments. The first impulse is to seek 

 shelter ; the second, which is the better, is to become as 

 supple as possible for flight and above all for attack- 

 attack being the most effective means of defence. So 



