2 On the Cortical Connexions of the Optic Nerves. [May 1, 



2. The origins of the optics may be divided into two sets 

 ganglinnic and cortical. 



3. The fibres in the ganglionic set are derived from the corpora 

 genicnlata, pulvinar and corpora qnadrigemina, probably also directly 

 from the substance of the thalamus. 



4. The cortical set join the chiasma and tract. 



5. The junction of the chiasma with the cerebral cortex is brought 

 about by means of "Meynert's commissure." The latter arises from 

 the lenticnlar-nncleus-loop (Linsen-kern-schlinge), decussates in the 

 lamina cinerea, and passes with the optic nerve of the opposite side. 

 This commissure is connected to the cortex in the frontal region by 

 the following means : 



It arises directly from the lenticular-nucleus-loop ; the lenticular- 

 nucleus-loop is formed by the junction, below the lenticular nucleus, 

 of the striae medullares ; the striae mednllares form part of the 

 fibres of the inner capsule, and the inner capsule is composed of the 

 fibres descending from the cortex. I should think it very probable 

 that the fibres constituting the striae medullares come from the cortex 

 of the same side. 



6. The other cortical connexions of the optic join the tract as it 

 winds round the pedunculus cerebri. They are the following : 



(a.) A large mass of fibres derived from the motor areas of the 

 opposite cerebral hemisphere, crossing in the corporus callosum, enter- 

 ing the outer capsule, and joining the tract directly. 



(6.) A great number of fibres uniting it to the temporo-sphenoidal 

 lobe of the same side, and especially the first and second temporal 

 convolutions. 



(c.) A bundle of fibres, which spreads out into the gyrus hippo- 

 campi of the same side. 



(d.) A large leash of fibres, which connects it directly with the 

 tip of the occipital lobe forming part of the " optic radiation." 



7. The tract is in all probability further connected to the cerebral 

 cortex indirectly, that is to say, by the intervention of the ganglionic 

 masses, in the following manner : To the occipital lobe of the same 

 side, through its connexion with the corpora geniculata and pulvinar, 

 and the continuation of fibres from these backwards. 



8. It is extremely doubtful whether the anterior corpus quadri- 

 geminum is connected to the occipital lobe of the opposite side by a 

 continuous band. 



9. The " optic radiation " of Gratiolet going to the occipital lobe 

 is composed of the following constituents : 



(a.) A branch to the optic tract directly. 

 (&) ., corpus geniculatum internum. 



(c-) .1 externum. 



(t/.) pulvinar. 



