372 ZOOTOMY, 



of the structures in the lateral ventricle, 498, 

 may be injured). Note : 



496. The central mass of white matter in each hemisphere, 

 and the superficial grey matter. 



497. The fibres of the corpus callosum, passing horizon- 

 tally outwards on each side, those in front curving slightly 

 forwards, those behind slightly backwards, to enter the sub- 

 stance of the hemispheres (Fig. 71, A, cp.d). Near the middle 

 line the surface of the corpus callosum is marked by two fine 

 white longitudinal lines, the striae longitudinales (st.t). 



LVIII. In laying bare the corpus callosum, a cavity, the 

 lateral ventricle ( 498) will probably have been 

 cut into : if not, carefully scrape away the brain 

 substance near the centre of each hemisphere, 

 about a quarter of an inch external to the pos- 

 terior boundary of the corpus callosum, until the 

 cavity is met with : lift up the edges of the 

 aperture, and with fine scissors cut away the 

 roof of the lateral ventricle, including the corpus 

 callosum, so as to expose the whole cavity on 

 the one side, to within one-sixteenth of an inch 

 of the middle line of the corpus callosum. 

 Make out : 



498. The lateral ventricles (Fig. 71, A, right side), or 

 cavities of the cerebral hemispheres, each of which is widest 

 in the middle (body of the lateral ventricle), tapers off 

 almost to a point anteriorly (anterior cornu), and ends 

 behind somewhat bluntly. 



499. The hippocampus major (hf.m\ a large white 

 eminence, of nearly semicircular section, forming the floor 

 of the body of the lateral ventricle, and extending outwards 

 and backwards : internally it passes into an area, the lyra, 

 by which it is united with its fellow of the opposite side. 



