The Body of a Bird 



3' 3 



in this and in many other so-called protectively coloured 

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



Fig 250. —Snowy Owl. Aggre-ssive 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 



