542 PHYSIOLOGY CHAP. 



soul. In conclusion therefore (and this is the pith of Kant's 

 metaphysical comment on Sommering's hypothesis) it is not 

 impossible for the physiologist to make the collective unity of all 

 the sense perceptions in a common organ intelligible, though he 

 who attempts to solve the problem of the seat of the soul is 

 handling the impossible, and may be confronted with the words of 

 Terence, " Incerta haec si tu postules ratione certa facere, nihilo 

 plus agas, quam si des operam ut cum ratione insanias." 



These remarks are necessary to the correct appreciation of the 

 physiological value of the work of Gall and his pupil and collab- 

 orator Spurzheim, the founders of the theory of cerebral localisa- 

 tion. They were the first who brought out the importance of the 

 grey matter of the cerebral cortex in general, and of the ganglia of 

 the nervous system, which they considered to be the origin of the 

 nerves and the organ of nutrition of the white matter. The 

 nervous system as a whole results from the association of several 

 separate systems, each of which has a different function. All 

 these systems, however, are united by means of commissures. 

 There is accordingly no common centre for all sensations, all 

 thoughts, all volitional impulses. Unity results from the harmony 

 of the individual functions brought about by the commissures. 



Again the cerebral hemispheres are divisible into as many 

 pairs of particular organs as the distinct functions which they sub- 

 serve. Intellectual phenomena depend exclusively upon the cere- 

 brum, and its convolutions are " the organs of the mind." Gall 

 excludes the sense organs from any direct participation in the 

 phenomena of the intellect. They do not develop in proportion 

 with intelligence, in fact the larger number of them even stand 

 in inverse ratio with it. Taste and smell are more developed in 

 lower mammals than in man ; vision and hearing are more acute 

 in birds than in mammals. The cerebrum alone develops in direct 

 proportion with intelligence. The loss of one or more senses does 

 not diminish intelligence, which may persist even after the loss of 

 all the senses. 



Gall, however, did not confine himself to the consideration of 

 the cerebrum as the substrate of mental phenomena ; he conceived 

 a psychological system, in which the intellect or psychical person- 

 ality of man is divided into a sum of arbitrary heterogeneous 

 faculties, each independent of the other, and each represented in a 

 special province of the cerebral cortex. 



Gall's so-called phrenology started with the observation made 

 in his schoolboy days, when he noticed that some of his fellow- 

 students who had a remarkable memory for words had prominent 

 eyes ; this led him to conclude that the faculty of verbal memory 

 was localised in that part of the frontal lobe which lay above and 

 behind the orbital cavity. 



If the capacity for learning easily by heart is associated with 



