324 A C7IONS NO T PUREL Y PHYSICAL. 



shown that certain lesions prevented the voluntary move- 

 ments of special groups of muscles, and thus the part of 

 the brain which presided over these was defined. In ex- 

 perimenting it is scarcely possible to avoid irritating a 

 comparatively considerable area of nerve tissue, and hun- 

 dreds and thousands of nerve fibres are suddenly thrown 

 into violent action ; but there is no doubt by pursuing this 

 method, and by repeated observations in well-marked cases 

 of disease, great additions will be made to the facts already 

 known concerning the mode of action of the grey matter of 

 the convolutions of the brain. 



Some may be led to infer that the interesting results of 

 experiments such as those referred to tend to establish the 

 conclusion that the action of the brain matter is purely 

 physical. But no such inference is justified. Certain nerve 

 fibres connected with those distributed to particular muscles 

 are artificially irritated, and as in all other cases, these 



tions grouped around it, have no motor signification, and are probably 

 connected with sensation. 



"8. The optic lobes or corpora quadrigemina, besides being con- 

 cerned with vision and the movements of the iris, are centres for the 

 extensor muscles of the head, trunk, and legs. Irritation of these 

 centres causes- rigid opisthotonus and trismus. 



' ' 9. The cerebellum is the co-ordinating centre for the muscles of 

 the eyeball. Each separate lobule (in rabbits) is a distinct centre for 

 special alterations of the optic axes. 



" 10. On the integrity of these centres depends the maintenance of 

 the equilibrium of the body. 



"n. Nystagmus, or oscillation of the eye-balls, is an epileptiform 

 affection of the cerebellar oculo-motorial centres. 



" 12. These results explain many hitherto obscure symptoms of 

 cerebral disease, and enable us to localise with greater certainty many 

 forms of cerebral lesion." 



See "West Riding Lunatic Asylum Report," 1873. Medical 

 "Times" and "Gazette," August 30, 1873, P- 2 33- 



