Destructive Rivalry i73 



its operation is negative in the main; it arrives at the salva- 

 tion of the race by a method wasteful and improvident. The 

 other method of encouraging the increase is evidently likely 

 to produce colonies of thousands while this is guarding its 

 hundreds. Later when higher forms of physical organs are 

 found developed by both of these types these organs assume 

 shapes in each according to the life led. Predatory crea- 

 tures are ranged, mailed and armed on one side, and peace 

 loving creatures, defenseless except by flight, on the other. 

 These latter are already compelled by their inheritance to 

 continue their lives in the associated relations for which 

 alone they are fitted, isolation is danger as well as dis- 

 comfort; while continued cultivation by survival and selec- 

 tion, of habits of tolerance of one another, confirms more 

 and more this destiny as higher organization is reached. 

 Yet from time to time a reversion in variation or admixture, 

 or a new development in environment, will create new cir- 

 cumstances in which the other type is needed. So when we 

 observe the ways of well established, highly organized ani- 

 mals, whose conduct is understandable, we see all degrees 

 of mingled habit and equipment persisting, and we see their 

 behavior to be compounded of all the previous phases 

 selected and combined according to environment. For ex- 

 ample, the wide plains where sheltering concealment and 

 treacherous attack are difficult, have their herds of large and 

 comparatively peaceful cattle, horses, deer, and the like, fleet 

 for escape, and social for organized life, and in those quali- 

 ties finding sufficient safety against all enemies but man. But 

 in the forests the inviting opportunities for shelter are also 

 those for concealment and ambush, and here the strong 



