60 THE STORY OF THE BIRDS. 
Its discussion would involve the exposition of anatom- 
ical details and changes in habit and in the digestive 
tract not practical in this little book. 
With changed habits or changed food supply 
came about certain special means of prey taking, de- 
veloping some utensils that were weapons indeed 
against everything, and some which were adapted only 
to the special needs. For instance, the beaks of cranes, 
shaped for piercing a fish or frog, makes a dog howl, 
but that of a swift or goatsucker, shaped for tak- 
ing flying insects, is harmless against an enemy. Of 
course, again, the hooked beak and terrible talons of 
the birds of prey are all-around weapons. So far as 
we can see, every modification of beak and claw of 
birds is made purely at the demands of food taking. 
In the true sense, therefore, these can not be taken 
as true weapons, except in their incidental use in de- 
fense. 
Our topic turns, therefore, upon speczal weapons, 
and the evidence is that these came in not as a neces- 
sity of procuring food, nor even for fighting an enemy 
of the species, but as a peculiar means of overcoming 
a rival—some fellow-sufferer in the toils of a charmer. 
Within the species war and love have come down the 
ages together. 
Mr. Darwin has shown that within the mammals, 
at least, many weapons are nearly useless against any- 
thing but a rival within the species, or at least have a 
poor use outside of this. One antelope has to get 
down on his knees and put his nose far back under 
himself to bring his horns into play. While this is 
