394 NEKVUPS SYSTEM. 



Their rounded base is directed forward, and the narrower 

 end, backward and outward. Their external surface is gray, 

 and they present, on section, alternate striae of white and 

 gray matter, w r hich appearance has given them the name of 

 corpora striata. Between the narrow extremities of these 

 bodies, are situated the optic thalami. 



There is very little to be said with regard to the func- 

 tions of the corpora striata. Longet has found them com- 

 pletely inexcitable and insensible to mechanical irritation. 1 

 The idea of M agendie, that a tendency to backward move- 

 ments resided in these bodies, while the cerebellum exerted 

 an antagonistic action, is not sustained by experiments. 8 

 When they are removed, disturbing the hemispheres as little 

 as possible, there appears to be no paralysis, either of motion 

 or sensation. 3 



"We have obtained a little more information regarding 

 the functions of the corpora striata, from cases of cerebral 

 haemorrhage in the human subject, than from experimental 

 investigations. In apoplexy, when the corpus striatum on 

 one side is alone involved, there is paralysis of motion of the 

 opposite lateral half of the body, the general sensibility usual- 

 ly being unaffected. Facts of this kind show that the action 

 of the corpora striata is crossed ; and they further illustrate 

 their connection with the motor tract from the hemispheres. 



There is no reason to suppose that the corpora striata are 

 the centres of olfaction, as was at one time thought, for they 

 are sometimes absent in animals possessing very large olfac- 

 tory nerves, and are very largely developed in the cetacea, 

 in which the olfactory apparatus is rudimentary. 4 



Optic Thalami. 



From their name, we should infer that the optic thalami 

 have some important function in connection with vision ; 



1 LONGET, Traite de physiologic, Paris, 1869, tome iii., p. 419. 



2 MAGENDIE, Precis elementaire de physiologic, Paris, 1836, tome i., p. 404. 

 8 LONGET, loc. cit. 4 LONGET, loc. cit. 



