The Body of a Bird ^i 2 



in this and in many other so-ealled in'otectively coloured 

 birds, otlier factors, such as the direct effect of light on 



Fig 250. — Snowy Owl. Aggres.'^ive coloration in an Arctic Owl. 



the plumage, enter into the causation, can only be solved 

 by future thorough investigation. 



Albinos are occasionally found among widely different 



