122 Comparative Morphology of Chordates 



important — the capacity for retaining nervous impressions, are all 

 more or less directly related to degree of intelligence, but they are 

 merely the necessary accompaniments of intelligence, not (either 

 singly or collectively) the source of it. Intelligence and the neencephalic 

 mechanism adequate for its operation always go together, but how 

 they have come to be thus associated is beyond present knowledge. 



Consciousness is something broader than intelligence. A person of 

 low intelligence may be keenly aware of his inferiority, and we are all 

 conscious of many of our unintelligent reflex and instinctive acts. We 

 are confident that our fellow human beings are conscious because they 

 act as if they were and they say they are. Other animals may act as if 

 they were but they cannot tell us about it. We cannot absolutely prove 

 that they are conscious. Granting that birds are dominated by the 

 "old" brain, we nevertheless feel quite sure that they are aware of 

 what they do instinctively. In fact, even a teleost fish, totally devoid 

 of pallial nervous structures, acts as if it were conscious. While there 

 are strong reasons for regarding the cerebral cortex as the seat of 

 intelligence, it seems "as good as certain" that vertebrates without 

 I lie cortex are conscious, even if only feebly intelligent. 



The "seat" of consciousness is highly problematic. We feel that it 

 is in the head. We are conscious of our feet but it seems to be via the 

 head that we are aware of them. In man and other mammals the 

 cerebral cortex (as shown by clinical and other evidence) is somehow 

 especially concerned with consciousness, as would be expected if the 

 cortex is the seat of intelligence. There is evidence, however, that 

 sensations of pain and pleasure may emerge into consciousness via 

 the thalami. All things considered, it is likely that consciousness is not 

 necessarily associated with or limited to any sharply defined region of 

 the brain. Our consciousness of ourselves seems somehow to include 

 the whole body at once. Instead of thinking of consciousness as pro- 

 duced in or emanating from a limited part of the brain, it seems easier 

 to think of it as associated with the entire brain, or possibly coextensive 

 with the whole nervous system, even to the tips of the twigs of all its 

 peripheral nerves, for the whole is a physiologically continuous system 

 of protoplasmic nervous elements. The word "protoplasmic" in the 

 foregoing sentence suggests further possibilities. Specialized cells 

 merely emphasize one or another of the several potencies which inhere 

 in all protoplasm. If consciousness is associated with nerve-cells, then 

 it may be, in lower degree or in some indefinable vague or dim way, 

 associated with all cells and therefore coexistent with all the living 

 substance of the body. If this should be the truth, then we can imagine 

 that the whole conscious field of the animal is somehow "polarized" 

 or brought to a "focus" at the region where the nervous tissue is most 



