398 



DISSECTION OF THE RABBIT. 



y. The posterior commissure is a small band of 

 transverse fibres in the roof of the hinder 

 end of the third ventricle, just in front of 

 the optic lobes. 



iii. The roof of the third ventricle has already been 

 seen and removed. 



Fiq. 71. Lepus cuniculus. A longitudinal and vertical section of the 

 brain, taken in the median plane, (a. m. m.) 



A, pituitary body. AC, anterior commissure. AF, anterior pillar of the 

 fornix, seen in the wall of the third ventricle. C, cerebellum. CA, corpus 

 albicans. CC, corpus callosum. CH, inner surface of left cerebral hemisphere. 

 F, body of the fornix. FM, foramen of Monro. G, roof of third ventricle. 

 I, infundibulum. MC, middle commissure. N, anterior optic lobe or ' nates.' 

 O, olfactory lobe. OC, optic chiasma. ON, left optic nerve. P, pineal body. 

 PC, posterior commissure. PV, pons Varolii. T, posterior optic lobe, or 

 ' testis.' VA, velum medullae anterius, or valve of Vieussens. VP, velum 

 medullae posterius. 



Ill, third ventricle. IV, fourth ventricle. V, so-called fifth ventricle. 



iv. The stalk of the pineal body is a tubular pro- 

 longation, upwards and backwards, of the 

 roof of the ventricle, just in front of the 

 posterior commissure. 



v. The optic chiasma appears in this section as a 

 thickening in the floor of the anterior end 

 of the ventricle. 



