IX.] 



THE NER VO US S YS TEM. 



371 



tending down into the infundibulum and bounded in front 

 by the lamina terminalis. This cavity is called the thira 



FIG. 326. THE BRAIN AS SEEN WHEN A VERTICAL LONGITUDINAL SECTION- 

 HAS BEEN MADE THROUGH ITS MIDDLE. 



Av, arbor vitae of the cerebellum ; c, cerebrum : cc, corpus callosum ; ^.corpora 

 quadrigemina ;_/", fornix (between the fornix and the corpus callosum is the 

 septum lucidum) ; m, medulla oblongata ; ma, corpus mammillare : on, optic 

 nerve ; pi, pineal gland ; pt, pituitary body ; pv, pons Varolii ; s, soft, ot 

 middle commissure. 



ventricle. A small aperture (the foramen of Monro) opens 

 immediately behind the anterior part of the fornix, and a 



FIG. 327. ENLARGED AND DIAGRAMMATIC VIEW OF A VERTICAL SECTION 

 CARRIED THROUGH THE CORPUS CALLOSUM AND THE PARTS BELOW. 



etc, anterior commissure ; cc, corpus callosum ; cbl, cerebellum ; cm, corpus 

 mammillare ; y^ fornix \_fnt, foramen of Monro ; /, infundibulum Ip, locus; 

 perforatus medius ; mo, medulla oblongata ; na, nates ; on, optic nerve ; pc, 

 posterior commissure ; pv, pons Varolii ; pi, pineal gland ; pt, pituitary body ; 

 s, soft, or middle commissure ; si, septum lucidum: t, lamina terminalis ; te, 

 testes ; v, velum interpositum (between it and the fornix is a space enclosed by 

 the folding over of the cerebrum upon the roof of the third ventricle) ; 3, upper, 

 and 3', lower part of third ventricle ; 4, fourth ventricle between them is the 

 iter a tertio ad qitartnm ventriculuw. 

 B B 2 



