GENERAL SURVEY OF THE STRUCTURE OF THE BRAIN. 371 



Figs. 230, 231, 232. A horizontal and two antero-posterior sections 

 of the brain of Vespertilio pipistrella, to illustrate the essential points 

 in the structure of the brain. General references : F, frontal region ; 

 O, occipital region ; Tp, temporal region of the cerebral hemisphere, 

 or proseiicephalon (Vorderhirnes) ; R, olfactory lobes ; S, septum 

 lucidum ; H, Gyrus hippocampi, with, /, the fornix ; T, the corpus 

 callosum ; a a, fibrae proprise of the cortex of the cerebrum (connect- 

 ing fasciculi) ; L, anterior and posterior cornu of the lateral ventricle ; 

 Cs Cs, ganglionic masses of the prosencephalon (corpus striatum 

 and lenticular nucleus, or corpus striatum internum and externum) ; 

 Th, ganglionic mass of the deutencephalon (optic thalamus, Sehhiigel) ; 

 P P upper segment or link of the projection system for the ganglionic 

 mass of the prosencephalon ; P,', upper segment of the projection 

 system for the ganglionic mass of the deutencephalon, with which 

 also / (the fornix) must be included ; Qu, the ganglionic masses of 

 the mesencephalon (corpora quadrigemina) ; Br, upper segment of 

 the projection system of the mesencephalon (brachia of the corpora 

 quadrigemina) ; L p, median portion of the floor of the mesence- 

 phalon (lamina perf orata posterior) ; P 2 , middle segment of the pro- 

 jection system, proceeding from the ganglia of the prosencephalon' 

 (crusta of the cerebral peduncle, cut off in fig. 232, on account of its 

 inclination towards the middle line ; in fig. 231, P 2 a, continued 

 through the pons) ; Tg, the middle segment of the projection system, 

 proceeding from the gaiiglionic masses of the deutencephalon and 

 mesencephalon (tegmentum of the cms cerebri) ; vm, the posterior 

 longitudinal fasciculi of the tegmentum ; Ca, the anterior commissure ; 

 Cm, the soft commissure of the optic thalami ; m, the central grey 

 substance of the cavity or ventricle of the deutencephalon (third 

 ventricle) ; J, the infundibulum ; Ag, the grey substance of the central 

 cavity of the mesencephalon (around the aquaeductus Sylvii) ; Gl, 

 pineal gland ; Cp, the posterior commissure ; Sc, the transverse fissure 

 of the cerebrum ; PI, plexus chorioideus ; 06, the cerebellum ; E, the 

 corpora restif ormia ; V, the pons Varolii ; P 2 a, the tract of the pyra- 

 mids (or continuation of the crusta of the cerebral peduncle) ; P 2 r, 

 continuation of the tract of the tegmentum in the projection system 

 of the pons and oblongata ; Kb, transverse section of the fasciculi of 

 the cerebellum ; Z, the transverse section of the stratum zonale ; Z), 

 the superior olivary body ; 0, apparent commissure of the superior, 

 olivary bodies; D', inferior oh' vary body ; Fr, the grey substance of the 

 central cavity of the region of the opisth- and ep-encephalon forming 

 the fourth ventricle ; Gr, the grey substance of the central cavity in 

 the region of the epencephalon and spinal cord around the central 

 canal (Oc) ; Fg, the slender fasciculus ; P 3 , the inferior segment of 

 the projection system in fig. 230, in the region of the mesencephalon, 

 forming the nervus oculo-motorius, and in the region of the post- 

 encephalon the nervus facialis ; in fig. 232, P 3 ', the fifth nerve ; P 3 ", 

 the facialis ; n, nervus opticus. 



BB 2 



