700 FUNCTIONS OF THE CEREBRO -SPIN AL NERVOUS SYSTEM. 



Up zygomatic action ; 8. Conjoint action of the elevators of upper lip and 

 depression of lower ; 9. Opening of the mouth and protrusion of the tongue ; . 



10. The retraction of tongue (these movements have a bilateral character) ; 



11. Action of platysma ; 12. Elevation of the eyebrows and eyelids, dila- 

 tation of the pupils, and turning the head to the opposite side; 13. Eyes 

 directed to the opposite side and upwards, with usually contraction of the 

 pupils ; 13'. Similar action, but the eyes usually directed downwards ; 14. 

 Retraction of the opposite ear, head turns to the opposite side, the eyes widely 

 opened and the pupils dilated ; 15. Stimulation of this region, which corre- 

 sponds to the tip of the uncinate convolution, causes torsion of the lip and 

 nostril of the same side. The antero-frontal and occipital regions give no 

 result on stimulation; nor does the island of Reil react to the stimulus. 

 Stimulation of the corpora striata caused tonic spasm of the whole of the 

 muscles of the opposite side, and consequently a condition of pleurostho- 

 tonos. Stimulation of the optic thalamus was negative. Considerable dif- 

 ference of opinion exists among experimenters as to the real signification 

 of the results thus obtained by galvanic or Faradic stimulation of the 

 surface of the hemispheres. Fritsch and Hitzig and Ferrier regard them 

 as the result of excitation of the gray matter of the cortex, while others 

 regard them as the result of conduction of the current to the motor ganglia. 

 Dupuy 1 and also Carville and Duret have attempted to prove that the 

 actions exerted are due to diffusion and conduction to underlying motor 

 ganglia :md motor strands. Dr. Burdon-Sanderson 2 has also shown that 

 when the gray matter corresponding to the centres defined by Hitzig and 

 Ferrier is removed, yet the same actions are produced by exciting the me- 

 dullary fibres which proceed from these to the corpus striatum. This fact 

 has also been stated by other subsequent experimenters. Ferrier 3 argues 

 that the results cannot be explained by conduction, on the ground that in a 

 state of anaesthesia sufficient to prevent any manifestation on stimulation of 

 the surface of the brain, the corpora striata still remain excitable; whence, 

 unless it be assumed that chloroform annihilates the conductivity of the 

 medullary fibres to the electric stimulus, the results should be obtained as 

 before. The definiteness and predictability of the results, and also the fact 

 that stimulation of the island of Reil, which is nearest the corpus striatum, 

 cause's no action, even though the rest of the brain is excitable, seem to dis- 

 pose of objections on the ground of conduction or diffusion. Even though 

 a certain amount of diffusion of the current beyond the points of contact ^of 

 the electrodes be proved, it would seem that a certain intensity is requisite 

 to produce stimulation, and the possibility of differentiating centres in close 

 proximity to each other would seem to prove the fact of localization. In 

 reference* to the experiments of Dr. Sanderson, Ferrier argues that as the 

 corpus striatum contains in an integrated form the centres individually dif- 

 ferentiated in the hemispheres, it is quite in accordance with the explanation 

 given by Hilzig and himself to suppose that stimulation of the medullary 

 cone of fibres should excite the same movements as result from functional 

 activity of the corresponding cortical centres. Considerable diversity of 

 opinion exists as to what relation these cortical centres have to the motor 

 phenomena which are manifested on stimulation. Fritsch and Hitzig are of 

 opinion that they are in some way related to the muscular sense, on the 

 ground that after the ablation of the limb-centres in dogs, the animals so 

 operated on do not suffer from paralysis of the limbs, but merely appear to 

 have lost consciousness of the position of the limbs, and hence place them 

 in irregular and unnatural attitudes. This view is also supported by Noth- 



1 Exiimcn de qwlquos Points de la Physiologic clu Orvt-au, Paris, 1873. 



2 Proe. Roy. Sue., 1873. 3 West Riding Asylum Reports, vol. iv, 1874. 



