682 REMOVAL OF THE CEREBRUM. 



points out that the characteristic features of lesions in the prefrontal cortical region are 

 afforded by "mychical disturbances, consisting of dementia, apathy, and somnolency. ] 



Imperfect development of the cerebrum. -Microcephalia and hydrocephalus yield every 

 result between diminution of the psychical activities and idiocy. Extensive inflammation 

 dTgeneration, pressure, amemia of tlie blood-vessels, and the actions of many poisons produce 



th Floure^Doctrine.-Flourens assumed that the whole of the cerebrum is concerned in 

 even, psychical process. From his experiments on pigeons, he concluded that, if a small part 

 of the hemispheres remained intact, it was sufficient for the manifestation of the mental 

 functions ; just in proportion as the grey matter of the hemispheres is removed all the 

 functions of 'the cerebrum are enfeebled, and when all the grey matter is removed all the 

 functions are abolished. According to this view, neither the different faculties nor the different 

 perceptions are localised in special areas. Goltz holds a somewhat similar view to that ot 

 Flourens. He assumes that if an uninjured part of the cerebrum remain, it can to a certain 

 extent i>erform the functions of the parts that have been removed. This Vulpian has called 

 the law of "functional substitution" (loi de suppleance). 



The Phrenological doctrine of Gall (t 1828) and Spurzheim assumes that the different 

 mental faculties are located in different parts of the brain, and it is assumed that a large 

 development of a particular organ may be detected by examining the external configuration ot 

 the head (Cranioscopy). 



Removal of the Cerebrum. After the removal of both cerebral hemispheres, 

 in most animals, every voluntary movement and all conscious impression and 

 sensory perception entirely cease. On the other hand, the whole mechanical move- 

 ments and the maintenance of the equilibrium of the movements are retained. 

 The maintenance of the equilibrium depends upon the mid-brain, and is regu- 

 lated by important reflex channels ( 379). 



Sudden cessation of the circulation in the brain, e.g., by decapitation, is followed at once by 

 cessation of the mental faculties. When Hayem and Barrier perfused the blood of a horse 

 through the carotids of a decapitated dog's head, the head showed signs of consciousness, and 

 will for 10 seconds, but not longer. 



The mid-brain (corpora quadrigemina) is connected not only with the grey matter 

 of the spinal cord and medulla oblongata, the seat of extensive reflex mechanisms 

 ($ 3G7), but it also receives fibres coming from the higher organs of sense, which 

 also excite movements reflexly. The corpora quadrigemina are also supposed to 

 contain a reflex inhibitory apparatus ( 361, 2). The joint action of all these 

 parts makes the corpora quadrigemina one of the most important organs for the 

 harmonious execution of movements, and this even in a higher degree than the 

 medulla oblongata itself (Goltz). Animals with their corpora quadrigemina intact 

 retain the equilibrium of their bodies under the most varied conditions, but they 

 lose this power as soon as the mid-brain is destroyed {Goltz). Christiani locates the 

 co-ordinating centre for the change of place and the maintenance of the equilibrium, 

 in mammals, in front of the inspiratory centre in the 3rd ventricle ( 368). 



That impressions from the skin and sense-organs are concerned in the maintenance of the 

 equilibrium, is proved by the following facts : A frog without its cerebrum at once loses its 

 power of balancing itself as soon as the skin is removed from its hind limbs. The action of 

 impressions communicated through the eyes is proved by the difficulty or impossibility of 

 maintaining the equilibrium in nystagmus ( 350), and by the vertigo which often accompanies 

 paralysis of the external ocular muscles. In persons whose cutaneous sensibility is diminished, 

 the eyes are the chief organs for the maintenance of the equilibrium ; they fall over when the 

 eyes are closed. [This is well illustrated in cases of locomotor ataxia (p. 647).] 



Frog. A frog with its cerebrum removed retains its power of maintaining its 

 equilibrium. It can sit, spring, or execute complicated co-ordinated movements 

 when appropriate stimuli are applied; when placed on its back, it immediately 

 turns into its normal position on its belly; if stimulated it gives one or two 

 springs, and then comes to rest ; when thrown into water, it swims to the margin 

 of the vessel, and it may crawl up the side, and sit passive upon the edge of the 

 vessel. When incited to move, it exhibits the most complete harmony and unity 

 in all its movements. Unless it is stimulated, it never makes independent, 

 voluntary, purposive movements. It sits in the same place continually as if in 



