CENTRAL NERVOUS SYSTEM. 271 



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

 sion derived from histological work to the effecl that the Bystem of the eallo- 

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



into the internal capsule of cither 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 ease of acute 

 lesions. Lesions of the corpora striata cause a rise in body-temperature. 1 

 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 mid 

 may last a week, but the temperature tends to return to the normal. The 

 most striking feature in these experiments 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. 2 

 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 dis- 

 proportion between the area of the lesion and the extent of the effects, it is 

 difficult to conceive 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 bulb, in which case the vessels supplying a great area are con- 

 trolled by a small group of cells. 



The difficulty of an anatomical explanation is increased by the fact that Ott 3 

 enumerates in animals six heat-centres: 1. The cruciate, about the Rolandic 

 fissure ; 2. The Sylvian, at the junction of the supra- and post-Sylvian fissures ; 

 3. The caudate nucleus ; 4. The tissues about the striatum ; 5. A point be- 

 tween the striatum and the thalamus, near the median line; (!. The anterior 

 mesial end of the thalamus. 



Thalamus. — In considering the thalamus, we find that the various cell- 

 groups forming it are connected with distinct portions of the cerebral cortex 

 by double pathways — one set of axones having their origin in cell-bodies 

 located in the cortex, and the other in cell-bodies in the subdivisions of the 

 thalamus. The relations between these two divisions have been specially 

 Studied by v. Monakow, 4 who finds by experiment that lesion of one part, 

 cither cortex or the thalamic nuclei, is followed by degeneration in the other 

 part, and that the location of the defeneration depends on that of the lesion. 



Further, it has been observed by Melius'' that the axones passing from the 



1 Aronsolm mid S:iolis: Archiv fur die gesammte Physiologie, 1885, Bd, xxxvii.; Richel : 

 Coviptrx nii/lux d,' VAcad. des Sciences, 1884; Ott: /.' ain, lSS'.t, vol. xi. 



2 Kaiser: Neurobgisches Cenlralblalt, 1895, No. 10. 'Ott: Loc at. 



4 Archiv fur Psychiatric mul Nervenkrankheiten, 1893, Bd. xxvii. 



5 Proceedings of the Royal Society, London, 18U4 and 1895. 



