156 Instinct and Intelligence 



Taking this fact, and also that of their subse- 

 quent histories into consideration, we conclude 

 that the brains of these beings possessed the 

 mechanism by which they might have expressed 

 their thoughts in intelligent speech, but that the 

 machine failed to work. Their sensory, motor, 

 auditory, visual, and tactile centres were, in 

 conjunction with the association areas of their 

 cerebral hemispheres, capable of performing 

 their ordinary functions, but the two former 

 important receptors of energy had been de- 

 stroyed, so that the sensations and ideas which 

 children usually acquire through these sense- 

 organs were not formed ; the consequence was 

 that the functions of the association areas of 

 these children's brains remained undeveloped, 

 until they had been brought into action by the 

 skilful training of their tactile sense-organs, and 

 corresponding sensori-motor nervous centres. 

 This training consisted in the persevering 

 exercise of the nervous matter forming the 

 tactile sense-organs of their fingers, and thus 

 in bringing their corresponding sensori-motor 

 cerebral centres into a high state of physio- 

 logical perfection. By a process of this kind 



