CENTRAL NERVOUS SYSTEM. 713 



Before leaving the cerebral hemispheres, mention of the fact should be made 

 that still other functions, control of the sphincter ani (Fig. 189), secretion of 

 saliva, and micturition can be roused by the stimulation of the cortex in the 

 appropriate region namely, in the region where the muscles and glands con- 

 cerned might be expected to have representation if they followed the general 

 law of arrangement. Changes in the production and elimination of heat from 

 the body follow interference with the motor region of the cerebrum, and the 

 removal of portions of the cortex in this region is followed by a rise in the 

 temperature of the muscles affected. 



In the encephalon, the cerebrum, and especially its outer surface, is the por- 

 tion the functions of which have been studied. The significance of the other 

 portions of the encephalon can be far less well determined. The disturbances 

 caused by the section and stimulation of the callosum have been studied by 

 Koranyi l and by Schafer 2 and Mott. It was found that complete section 

 of the corpus callosum was not followed by any perceptible loss of function. 

 On the other hand, stimulation of the uninjured callosum from above gave 

 symmetrical bilateral movements, while if the cortex on one side was removed 

 stimulation of the callosum gave unilateral movements on the side controlled 

 by the uninjured hemisphere. These results seem to corroborate the conclu- 

 sion derived from histological work to the effect that the system of the callo- 

 sum is composed only of commissural fibres and that it sends no fibres directly 

 into the internal capsule of either side. Concerning the corpora striata and 

 the optic thalami very little is known. In the case of the corpora striata injury 

 causes in man no permanent defect of sensation or motion, although both forms 

 of disturbance may at the outset be present in the case of acute lesions. Lesions 

 of the corpora striata cause a rise in temperature. 3 Following a puncture of one 

 corpus striatum there occurs in rabbits a rise amounting to some 3 C. : it 

 begins a few minutes after the operation and may last a week, but the temper- 

 ature tends to return to the normal. The most striking feature in these exper- 

 iments is the very wide effects produced by an extremely small wound, like the 

 puncture of a probe. 



In the cases where lesion of the striatum on one side causes in man a rise of 

 temperature it appears mainly on the side of the body opposite the lesion. 4 

 A vaso-motor dilatation occurs over the parts of the body where the temper- 

 ature is high. 



In less degree a rise of temperature follows injury of the optic thalamus 

 at least such is the result of experiments on rabbits but the effect of the lesion 

 is never so marked as in the case of the striatum. Owing to the disproportion 

 between the area of the lesion and the extent of the effects, it is difficult to con- 

 ceive of the anatomical relations which permit the reaction. It is of interest 

 to note, however, that similar relations hold for the vaso-motor centre in the 



1 Archiv fur die gesammte Physiologic, Bd. xlvii. 2 Brain, 1890. 



3 Aronsohn und Sachs: Archiv filr die gesammte Physiologic, 1885, Bd. xxxvii. ; Bichet: 

 Compt. rend, de FAcad. des Sciences, 1884 ; Ott : Brain, 1889, vol. xi. 

 * Kaiser: Neurologische Centralblatt, No. 10, 1895. 



