338 THE ZOOLOGIST. 



of the deeper waters.* The sight perception of fishes is clearly 

 a phenomenon, of which we have practically the smallest in- 

 formation, and the scantiest imagination. 



It is even probable, as Bernstein has proposed, that the per- 

 ception of the external world is essentially an act of the mind, 

 which has its seat in the cerebrum, and is connected with this 

 organ ; and, further, that the sensory organ, with its nervous 

 connections, only affords the brain the material which it converts 

 into a Sensory Perception.! For it has been observed with 

 Pigeons, that upon the removal of the cerebral hemispheres, in 

 which state they may live for some time, they still possess a 

 sensation of light, which penetrates the eye, and causes a con- 

 traction of the pupil ; an action which can only be caused by the 

 central organ of the optic nerve in the brain. But a compre- 

 hension of the objects seen — i. e. a true perception of the senses 

 — is no longer possible to these animals. They behave like blind 

 animals, run against every obstacle, and no longer possess the 

 power of recognizing the objects seen as belonging to the external 

 world, t 



If it is granted that the perception of the external world is 

 essentially an act of the mind, and has its seat in the cerebrum of 

 man, and that Pigeons are proved to have the same relation be- 

 tween their sight perceptions and the integrity of their cerebral 

 hemispheres, then we cannot hesitate to apply the qualifying 

 influence of difference in evolution of cerebral matter between 

 man and other animals as largely modifying their power of 

 equally appreciating by sight the shape, colour, and size of the 

 different natural objects around them. We may therefore pause 

 before concluding that the insectivorous mammal, bird, or rep- 

 tile sees as we do the " protective " or " non-protective " shape 

 and colouration of its prey, or that the bird to the insect, or the 

 insect to the bird, appears to each, as both to ourselves. And so 

 with all that we consider " warning colours," a great element of 

 error may exist in our calculations, owing to a difference in the 

 sense perceptions of the animals most clearly interested in the 

 theoi'y formulated. 



* ' Natural Science,' vol. vii. p. 56. 



i Cf. ' The Five Senses of Man,' p. 163. I Ibid. pp. 162-3. 



(To be continued.) 



