John Hughlings Jackson. 



xxm 



complex combinations. It is needless to give the scheme of sensory centres. 

 The main conclusions are (1) that the highest (chiefly) sensory centres — 

 parts behind Ferrier's sensory region — and also the highest (chiefly) motor 

 centres — parts in front of the so-called motor region — make up the physical 

 basis of consciousness ; and (2) that just as consciousness represents, or is, 

 the whole person psychical, so its basis (highest centres) represents the 

 whole person physical — represents impressions and movements of all parts 

 of his body, in old-fashioned language, the highest centres are potentially the 

 whole organism. States of consciousness attend survivals of the fittest states 

 of centres representing the whole orgauism " (Ibid.). 



As to his highest levels and their situation in the brain his views do not 

 claim to be more than speculations, and much will have to be done before 

 they can be accepted as of higher value. 



It is of interest that his views as to the function and mode of action of 

 the cerebellum have been in all essentials confirmed by recent experimental 

 research. He says : — 



" All the muscles of the body are innervated both by the cerebrum and 

 cerebellum, but in an inverse order. The cerebellum regulates the muscular 

 contractions necessary for our attitudes in space, while the cerebrum 

 regulates the contractions necessary to effect all changes of attitude which 

 are made in response to successive impressions occurring in time. Speaking 

 broadly, then, the cerebellum regulates continuous or tonic muscular con- 

 tractions. It will be seen, therefore, that every combined muscular adjust- 

 ment necessitates the co-operation of both these organs ; no change of 

 attitude can be effected by the cerebrum except in so far as a certain 

 attitude was previously maintained by the cerebellum, and no steady move- 

 ments can be produced by the alternate contractions of some groups of 

 muscles, except in so far as other groups of muscles are maintained in a state 

 of continuous contraction. Hence it may be inferred that all movements of 

 the body are co-ordinated both in the cerebellum and the cerebrum." 



He ingeniously explained many of the phenomena of disease associated 

 with rigidity or contracture, such as paralysis agitans, hemiplegic and 

 paraplegic contracture, by unantagonised cerebellar influx, owing to cessation 

 or diminution of the influence of the cerebral hemispheres. 



The above extracts convey only a meagre sketch of the chief fundamental 

 principles which he applied to the elucidation of the phenomena of disease 

 with so much originality and fruitfulness. 



Jackson was a bad teacher in the ordinary sense, and lectured over the 

 heads of the rank and file of his students. Yet, in spite of all this, there 

 was never any unseemly behaviour in his class, such as occurred in that of 

 some of his colleagues, or wherever a teacher is not en rapport with his 

 pupils. Though he was essentially unpractical in a worldly sense, no one took 

 liberties with him, and he enjoyed the reputation of being a genius, and on 

 a higher level than ordinary men. He was not only revered, but beloved by 

 all with whom he came in contact. He was utterly devoid of self-seeking. 



