372 ZOOLOGY. 
Attached to a downward prolongation (infundibulum) of the 
optic thalami is the curious pituitary body. The medulla 
sends nerves to the skin and muscles, giving sensibility and 
motion to the face, eyes and nose, to the ldrynx and sensitive 
portion of the lungs; a pair also is sent to the lungs and 
heart. If the spinal marrow is severed, the parts below are 
paralyzed ; if the medulla is cut or broken up mammals die 
at once, while the lower Vertebrata die sooner or later. 
The brain in an embryo originally consists of three vesi- 
cles or primitive lobes; and the correspondence between 
% 
a) 
Fig. 367.—Diagrammatic, longitudinal and vertical section of a Vertebrate brain. 
Mb, mid brain; what lies in front of ‘this is the fore brain, and what lies behind, the 
hind brain. JZ, iamina terminalis; Olf, olfactory lobes; Hmp, cerebral _hemi- 
spheres; 7% Z, thalamencephalon; Px, pineal gland ; Py, pituitary body; FW, fo- 
ramen of Munro; CS, corpus striatum ; 72, optic thalamus; oF corpora quadri- 
gemina; CU, crura cerebri; Cd, cerebellum ; PV, pons varolii; MO, medulla oblon- 
gata; J, olfactorii; ZZ, opts 3 JZ, point of exit from the brain of the Motores 
oculorum ; ZV, of the pathetici . Vi , of the abducentes ; V-XZZ, origin of the other 
cerebral nerves ; 1, olfactory ventricle ; 2, lateral ventricle ; 3, third ventricle; 4, 
fourth ventricle.—After Huxley. 
the three primitive lobes, called respectively the fore, mid, 
and hind brain, may be seen by the following table : 
TABULAR VIEW OF THE SUBDIVISIONS OF THE VERTEBRATE BRAIN. 
( Olfactory lobes or ganglia, with their ventricles (rhinen- 
cephalon). 
Cerebrum or cerebral lobes or hemispheres (with the 
two lateral or first and second ventricles, forming 
the prosencephalon or prothalami). 
Optic thalami, with the third ventricle and conarium 
above and hypophysis (pituitary body) below 
(Thalamencephalon pineal gland). 
Fore brain. < 
