ii6 



THE BIOLOGY OF BIRDS 



(2) the organism may adjust itself effectively to its environ- 

 ment by controlled movements, and (3) to bind the body 

 into one (integration) so that each part, through the central 



OLL 



ORL PIT 



Fig. 27. — The brain of a pigeon, seen from'above, from below, and 

 from the side. From a specimen and model, ol.l., olfactory lobes; 

 CB., cerebrum; P. b., pineal body; OP.i.., optic lobe; cbl., cerebellum ; 

 N., nerve issuing from spinal cord (s.c.) ; O.N., optic nerves crossing as 

 they enter the brain ; pit., pituitary body ; m.o., medulla oblongata. 



system, can be connected up with any other, and so that 

 the numerous vital activities are harmonised. 



The nerve-fibres, Avhich compose the nerves, may be 



