252 DOMESTICATED ANIMALS 



even where its first influences are felt, the olden societies of 

 nature are disturbed or broken up. All the nobler members 

 of these associations, the greater mammals, many of the 

 laro-er birds, and a host of the lesser forms, are expelled or 

 destroyed. In the condition of organic life when the 

 supremely predatory creature man rose to domination, the 

 species were grouped in those vast organizations which were 

 of old termed faunae and florae, but which are now better 

 known as biological fields or provinces. In each of these 

 hosts the several species were, as regards their external life, 

 so balanced with their neighbors that the assemblage from 

 the point of view of these relations might well be compared 

 with the polities or states of man's construction. Such an 

 organic society represents the result of a series of trials and 

 balances which began to be made in the immeasurably remote 

 past and have been continued through the geologic ages, 

 each age adding something to the accord. The plants give 

 and take from the animals ; the insects are equated with the 

 birds, and each species in every group has set up an accord 

 with its rivals. From time to time the host has by the 

 changes of sea and land been compelled to migrate, moving 

 this way and that to find its fit station. In these move- 

 ments species are rapidly extinguished, much as the weaker 

 soldiers of an army perish in forced marches. Into their 

 places new forms hasten to take their place, so that every 

 position of advantage is filled. At a less rapid rate, but 

 perpetually, even without the change of abode, which it is 

 often by climatic changes compelled to make, the organic 

 host is slowly changing in character; old kinds give way in 

 the endless contest to new varieties which have managed to 

 establish a better relation to the environment. Still the 



