THE EVOLUTION OF LANGUAGE 199 



The success of the co-operative principle, how- 

 ever, depends upon one condition : the members of 

 the herd must be able to communicate with one 

 another. It matters not how acute the senses of each 

 animal may be, the strength of the column depends 

 on the power to transmit from one to another what 

 impressions each may receive at any moment from 

 without. Without this power the sociality of the 

 herd is stultified ; the army, having no signalling 

 department, is powerless as an army. But if any 

 member of the herd is able by motion of head or 

 foot or neck or ear, by any sign or by any sound, 

 to pass on the news that there is danger near, each 

 instantly enters into possession of the faculties of 

 the whole. Each has a hundred eyes, noses, ears. 

 Each has quarter of a mile of nerves. Thus num- 

 bers are strength only when strength is coupled 

 with some power of inter-communication by signs. 

 If one herd develops this signalling system and 

 another does not, its chances of survival will be 

 greater. The less equipped herds will be slowly 

 decimated and driven to the wall ; and those which 

 survive to propagate their kind will be those whose 

 signal-service is most efficient and complete. Hence 

 the Evolution of the signal-system. Under the 

 influence of Natural Selection its progress was in- 

 evitable. New circumstances and relations would 



