EFFECTS UPON THE PUPIL. 



fornicatus), while from some other parts of the cortex vaso-coristriction 

 was obtained. We did not, however, feel justified from our experiments 

 in concluding that there was a definite localisation for the production 

 of vaso-constriction and vaso-dilatation in the cortex, but supposed that 

 we were exciting sensory regions, and that the difference of the results 

 obtained was analogous to that obtained on stimulating different 

 afferent nerves. 



The circulatory effects of cerebral excitation have been very fully 

 studied by Franc^ois-Franck and Pitres. 1 They obtained, as the results 

 of simple excitations uncomplicated by epileptic after-effects, with quiet 

 and very slightly anaesthetised animals (dogs), only constrictor effects 

 upon the blood vessels, 

 often followed, however, by 

 vaso-dilatation ; the latter 

 effect was never obtained 

 primarily under these con- 

 ditions ; the effects were 

 general, not localised, and 

 not confined to the op- 

 posite side ; they were 

 most marked when the 

 electrodes were placed on 

 the motor zone, but were 

 also manifested when the 

 adjacent regions were 

 stimulated, but not if the 

 stimulations were applied 

 at some distance from that 

 zone (unless epilepsy was 

 produced). The effects 

 upon the heart-beat were 

 very variable sometimes 

 it was accelerated, some- 

 times slowed these differ- 

 ences appearing not to 

 depend upon the seat of 

 excitation, but partly upon 

 the strength of current 

 and partly upon the con- 

 dition of excitability of the 

 cortex. 



Effects upon the pupil. Excitations which are sufficient to provoke 

 epilepsy are always provocative of dilatation of the pupil, no matter to 

 what part of the cortex they are applied (Franck and Pitres). On the 

 other hand, weaker excitations do not affect the pupil, except when 

 applied over the regions which are connected with movements of the 

 eyes and head. Here it was found, both in the monkey and dog, 

 by Ferrier, that if the electrodes were applied to the anterior part of 

 the motor area, the movements of the head and eyes were usually 

 accompanied by opening of the eyelids and marked dilatation of the 

 pupils. The same is the case when the electrodes are applied over the 

 posterior part of the hemisphere (visual region). On the other hand, 



1 Fran9ois-Franck, loc. cit. 



FIG. 326. Effects upon the volume of the kidney 

 (Vol. JR.) and arterial pressure (P.O.) of exciting 

 the motor area of the cerebral cortex of a dog. 

 The very great rise of pressure in this experiment is 

 due to the fact that the animal was atropinised, so 

 that the cardio-inhibitory effects which are usually 

 also produced were absent. Fran9ois-Franck and 

 Pitres. 



