SOME PHYSIOLOGICAL ASPECTS OF HYPNOTISM. 517 



In all higher animals, such as Vertebrates, the nervous 

 system consists of peripheral nerves and central nervous 

 substance, the latter being situated in the bony canal of 

 the spinal column as the spinal cord, and in the skull as 

 the cerebral hemispheres, cerebellum and medulla. 



The central masses contain nerve-cells and their 

 branches ; these branches may be short or long, some 

 of the long branches form the essential vital portions of 

 the nerves, the so-called nerve-fibres. There is no nerve- 

 fibre which is not the process of a nerve-cell ; cut off from 

 this the fibre becomes functionless. It further appears 

 probable that no nerve-fibre is the branch of more than one 

 nerve-cell ; each fibre by its course lays down an inde- 

 pendent structural path, and although this may divide and 

 subdivide indefinitely it remains distinct. Every nerve-cell 

 with its branches thus forms a complete nervous microcosm, 

 or, as far as the structural path it offers is concerned, a neuron. 

 These may be said to be the two great discoveries of 

 modern neurology, and it is in the light thrown by their 

 realisation that physiological knowledge of the nervous 

 system has to progress. A further fact, the discovery of 

 which preceded those just referred to, is connected with the 

 development of nerve. Xerve-fibres have grown from cells 

 to or from muscles and sensory organs, and innumerable 

 branches within the central nervous system have grown 

 from the cells of one part to and near the cells of a more 

 remote part, both in the spinal cord and the higher cerebral 

 masses. 



.Sensory or up-lines of nerve communication thus exist 

 from external sense organs to definite portions of the re- 

 cipient masses ; motor or down lines from localised groups 

 of cells in the central mass to muscular and other structures. 

 Between the ends of the up lines in the central nervous mass 

 and the commencement of the down lines in this mass, 

 between the arrival and the departure platforms, is a gap 

 unbridged by such nervous structures. The physiological 

 pecularities due to the existence of these gaps are those to 

 which I especially desire to direct attention. 



The more complex the central mass, the more tangled 



