PHYSIOLOGY: PRACTICUM X: PLATE XXIV. 

 SHEEP'S BRAIN, THE PARACCELES (lateral ventricles) EXPOSED ; X 2. 



4 , 



olfactory bulb 

 transected. 



PRECORNU 



2 

 genu 



hemiseptum 



PSEUDOCCELE 

 caudatum 



PARAPLEXUS 

 callosum 



- HIPPOCAMP 

 splenium 



MEDICORNU 



3 



This figure represents a stage of dissection intermediate between Plates XVIII and XXII. 

 By the removal of successive slices the PARACCELES have been opened ; the left has then 

 been more completely exposed by oblique sections, and the PARAPLEXUS trimmed off 

 so as to expose the wide FIMBRIA and the furrow between it and the HIPPOCAMP. The 

 plane of section did not coincide exactly with the CALLOSUM ; the caudal three-fifths of 

 this is represented by the transverse lines ; also the cephalic end, the GENU ; but an in- 

 termediate portion is wholly removed, exposing the narrow PSEUDOCCELE ("fifth ven- 

 tricle") and its thin lateral walls, HEMISEPTUMS. The HEMISEPTUM is here shown 

 to be only a porion of the general mesal wall of the paraccele. The Pseudocrele (PI. 

 25) has no connection with the true cavities of the brain. The only communications of 

 the paracceles are through the PORTAS with the mesal AULA (PI. XXII). 



The two FIMBRIAS and HIPPOCAMPS connected by a mesal part (PI. XXV) consti- 

 tute the FORNIX. 



The HIPPOCAMP is sometimes called hippocampus major. 



i, INTERCEREBRAL FISSURE. 2, CALLOSAL FISSURE. 3, VESSEL. 4, inter- 

 rupted lines indicating the continuation of the paraccele into the RHINOCCELE. 5, 

 PRECORNU. 6. CAPUT of the CAUDATUM. 7, SYLVIAN FISSURE crossed by 

 ARACHNOID. 8, VESSEL at bottom of fissure. 9, CAUDA of CAUDATUM. 10, part 

 of caudal wall of paracoele. 



