Functions of the Basal Ganglia. 631 



So there is no reason to doubt that in the thalamencephalon of the 

 fishes, such co-ordination is accomplished as their cerebral development 

 requires, in the same way as it is by the optic thalamus of the more ad- 

 vanced vertebrates. 



Monakow concluded, from experiments, that each " nucleus of the 

 optic thalamus is related to a particular tract of the cerebral cortex. He 

 concluded that the posterior nucleus ( fig. 348, 7 ) is related to the basal 

 regions of the hemisphere, the pulvinar and corpus geniculatum ex- 

 ternum (fig. 348, 5) to the occipital visual region, the corpus genicu- 

 latum internum (fig. 348, 6) to the temporal or auditory region, the ex- 

 ternal nucleus ( fig. 348, 3 ), and neighboring parts, to the upper and 

 lower parietal regions, and the anterior tubercle and median nucleus 

 (fig. 348, 2, 1) to the frontal regions of the hemisphere." It is too 

 soon to be quite sure of these details. Further investigation and exper- 

 iment is required. ( Ferrier. ) 



According to Lu}~s, the optic thalamus is divisible into four sections, 

 each of which is related especially to the condensation of a special 

 class of sensations. The anterior of these centers of sensation, is the 

 ganglion of the olfactoiy sense, the second the ganglion of sight, the 

 third that of touch and general sensation, and perhaps including taste, 

 and the posterior ganglion that of hearing. There are many facts 

 which support this subdivision of the optic thalamus. Hunter gives 

 the case of a young woman, " who in three years successively lost the 

 senses of smell, sight, hearing and sensation, and who gradually sank, 

 remaining a stranger to all external impressions." It was found that 

 the optic thalami alone had been affected, and they had been gradually 

 destroyed by a fungus haematodes. Dr. Auguste Yoisin tells of a case 

 in which smell on one side was lost, accompanied by degenerations of 

 the anterior ganglions of the thalamus. Serres reported a case of loss 

 of sight caused by hemorrhagic effusion of the middle centers, or sec- 

 ond ganglions. Luys observed two cases of loss of sensation on one 

 side, accompanied by the destruction of the " median center, " third gan- 

 glion, of the opposite side only; also in two cases of deaf mutes he 

 found the trouble to be located in the posterior ganglions of the optic 

 thalami, in one case a lesion, in the other an amyloid, or starchy degen- 

 eration of the parts. Luys is also of the opinion that stimuli reach the 

 optic thalami from the visceral or vegetative organs, and are co-ordi- 

 nated there like the stimuli from the senses and the cerebrum. When 

 the co-ordination of the external stimuli takes place in the optic thala- 

 mus, without the intermixture of the memory stimuli from the cere- 

 brum, the result is the automatic or instinctive sensori-motor actions. 

 In man, this class of actions is not nearly so large relatively as it is in 

 those animals possessing smaller development of cerebrum. Notwith- 



