SENSORY GANGLIA. CONSENSUAL ACTIONS. 703 



is lodged in the midst of parts whose function is altogether different, yet there 

 seems no reason for doubting that it has a character of its own, and that it is 

 really the ganglionic centre of the Auditory nerve. In like manner, we may 



Fig. 189. 



Section of the cerebrum, displaying the surfaces of the corpora striata, and optic thalami, the cavity of the 

 third ventricle, and the upper surface of the cerebellum. a e. Corpora quadrigemina, a testis, e nates. 

 b. Soft commissure, c. Corpus callosum. /. Anterior pillars of fornix. g. Anterior cornu of lateral ventricle. 

 kk. Corpora striata. IL Optic thalami. * Anterior tubercle of the left thalamus. z to s. Third ventricle. In 

 front of z, anterior commissure. 5. Soft commissure, s. Posterior commissure, p. Pineal gland with its 

 peduncles, n n, Processus a cerebello ad testes. m m. Hemispheres of the cerebellum. It. Superior vermiform 

 process. L Notch behind the cerebellum. 



probably fix upon a collection of vesicular matter, imbedded in the Medulla Ob- 

 longata which is considered by Stilling to be the nucleus of the G-losso-pharyn- 

 geal nerve, and to which a portion of the sensory root of the Fifth pair may be 

 also traced as representing the Gustatory ganglion. 



730. At the base of the Cerebral Hemispheres, we find two other large gan- 

 glionic masses, on either side ; through which nearly all the fibres appear to pass 

 that connect the Hemispheres with the Medulla Oblongata. These are the 

 Thalami Optici and the Corpora Striata. Now, although these are commonly 

 in the light of appendages, merely, to the Cerebral Hemispheres, it is evident, 

 from the large quantity of vesicular matter they contain, that they must rank 

 as independent ganglionic centres; and this view is supported alike by the evi- 

 dence of Comparative Anatomy, and by that afforded by the history of Develop- 

 ment. For it is certain that the size of the Thalami Optici and Corpora Striata 

 presents no more relation, in different tribes of animals, to that of the Cerebrum, 

 than does that of the ganglia of Special Sense ; and they may even present a 

 considerable development, when the condition of the Cerebrum is quite rudi- 

 mentary. Thus in the Osseous Fishes, a careful examination of the rela- 

 tions of the body which is known as the Optic lobe (Fig. 171, c) makes it ap- 



