978 Dynamic Theory. 



of either motor control or sensation; so that we, or the general person- 

 ality represented in the brain, have in general no sense of what sensi- 

 bility there is in those centers. But if something extraordinary happens 

 down there, as a blow upon the pit of the stomach, the sensation aroused 

 there overflows up to the brain and agitates the sensory centers there. 

 There are a number of subordinate plexuses which are tributary to the 

 solar plexus, and which, perhaps, act as brains for the special organs 

 with which they are in association. Thus, as we go away from the cen- 

 tral controlling ganglions, we find sub-ganglions in special control of 

 smaller districts and subject to the central authorities in all matters that 

 require the co-operation of other parts. Likewise we may suppose that 

 sensibility thus subdivides, and that the action of the smallest collec- 

 tions of nervous elements are regulated by small and special sensibili- 

 ties, having their seats in the same ganglions. It would seem there- 

 fore that the brain is not the center for the special control of the vege- 

 tative functions, and by analogy may be supposed to be not the center 

 for all the common sensibilities of the vegetative system; and by no 

 effort can it either control it by the will or find out its condition through 

 sensation. 



With the outside of the body the case is different, although the prin- 

 ciples are the same. The brain belongs to the outside in a special man- 

 ner. It is developed from th'e outer skin in the first place, and the sense 

 organs and muscles are likewise products of the first and second layers 1 , 

 the whole constituting the outside half of the body. The differentia- 

 tions which have concentrated sensibility in the brain, place it in a far 

 more intimate relationship with the outside than the inside, and far 

 less, in proportion, of the original sensibility remains to the tissues of 

 the outside. As observed above, all the sense organs located about the 

 head have their ganglions inside the cranium. If any sensibility re- 

 mains not concentrated in the brain, it is in the ganglions of the spinal 

 cord. These ganglions constantly change afferent stimulations into 

 motor ones, and do this when disconnected from the brain. But unless 

 they are connected we get no sensation of either the afferent or efferent 

 stimulations. Yet it is maintained by some writers 2 , that the sensibil- 

 it}' is there, but is as if it were the function of another person, because 

 it is disconnected or "inhibited" from the rest of the personality. 

 We have seen that there are direct connections between the spinal gang- 

 lions and the cerebrum, from which it might be inferred that the brain 

 has assumed the function of sensibility in part at least, for these local- 

 ities. Whatever stimulation there may be in the extremities or any- 

 where on the skin, we are liable to become sensible of it, and if it 

 be at all unusual, as a scratch, bruise, blow, &e. , we are pretty sure to 



1 See table X, page 64. 2 See G. H. Lewes, Problems of Life and Mind. 



