1-^8 Joi'UNAI. OF C()MPAKAT1\'K NeUUOLOGY. 



lines; some, after passing through the" red nucleus," unite 

 with this bundle, and then go in the same direction. 



Relations to the Optic Tracts. — Let us first consider these 

 in the human brain. The optic nerves [Edinger', p. 77] 

 after crossing at the chiasma (he does not mean complete de- 

 cussation) become the optic tracts; these turn around the 

 cerebral peduncles, and passing up behind the thalami, 

 spread out, partly entering them, but with other branches 

 going to the cerebellum and to the nidulus of the oculor- 

 motor nerve. He thinks that some fibres that enter the 

 thalamus, go no further, but that others do, by 'way of 

 the tract towards the cortical optic centres (the occipital 

 convolutions of the hemispheres). Iii the neighborhood 

 [Stilling', p. 474J of the optic lobes the tract divides into 

 three branches. The first runs through and partly around the 

 external geniculate body, and in a band thus covering the 

 gray substance of this body, passes to the surface of the 

 thalamus and runs on further (that is, to the cortical optic 

 centres; see Edinger's opinion just above). The second, 

 passing through the two geniculate bodies, and then giving 

 off a small shoot, which loses itself in the taenia, reaches the 

 corpora quadrigemina, where it divides into two branches, of 

 which the one penetrates the nates, and the other, passing by 

 on the surface and again dividing, partly forms a commissure 

 with its fellow and partly goes to the frenulum. The third 

 goes to the internal geniculate body, some of its fibres stop- 

 ping there, but most of them, passing on, go to the nates or 

 to the anterior cerebellar peduncles which can only partly be 

 regarded as a branch of the opticus; its connection with the 

 testes is certain. 



Associated with the optic fibres in the teleosts | Bellonci", 

 p. 7] are (1) the inferior commissure, which largely corres- 

 ponds with Gudden's commissure and is in connection with 

 the inferior lobes; (2) the fibraj ansulatai, which cross mostly 

 above, but also partly within the inferior commissure, as in 

 tlic reptiles and amphibians; (3) a small number of thick 



