CEREBRAL FUNCTIONS. 585 



non-mental, duties. If the cerebral hemispheres be re- 

 moved from a frog, the ajnmal^ can ._. still perform^ e^or 



nn longer, performs 



it .. must _be_ aroused by an immediately 

 acting stimulus,, and its response to this is as invariable 

 a^^rejdicable as that of a frog with its spinal cord only. 

 The movements which can be educed are, however, far 

 more complex; instead of mere kicks in various directions 

 the animal L can walk, leap, swim, get off its back on to its- 

 feet, and so on. Similar results are observable in pigeons 

 whose fore-brain has been removed; mammals bear the 

 operation badly, but some, as rats, survive it several hours 

 and then exhibit like phenomena. The creatures can move, 

 but do not unless directly stimulated; all tlieir volitional 

 spontaneity is lost, and, apparently, all^ perceptions also; 

 they starTat 'aloud' noise, but do not run away as if they 

 conceived danger; they follow a light with the eyes, but do- 

 not attempt to escape a hand stretched forth to catch them; 

 "they can and do swallow food placed in the mouth, but 

 would die of starvation if left alone with plenty of it about 

 them, the sight of edible things seeming to arouse no idea 

 or conception. It may be doubted, perhaps, whether the 

 animals have any true sensations; they start at sounds, 

 avoid qpacnie objects in their road, and cry when pinched; 

 but all these may be unconscious reflex acts f on the whole 

 it seems morejn-obable, however, that they have sensations 

 _but not percepjjgjtisj they feel redness and blueness, hard- 

 ness and softness, and so on: but sensations, as already 



pointed OUt^tell in_bliejnSPlvfia nothing; t-1^y nrp hnt. aifrr^ 



which have to bejiientally interpreted as indications of ex- 

 ternal objects: it is this interpretingpower which seems 



^deficient m the animal deprived of its fore brain. 



Functions of the Medulla Oblongata. This contains 

 the pgjJTg of conduction between thejoarts^of thejimin in 



jfront of it and^jth_gpjnjl_cj[ird. It is also the _s_eat. _of 

 _many important reflex and automatic centres, especiaU-- 

 those governing the organs immediately concerned in the 

 maintenance of life; as the respiratory, circulatory, _andL 

 masticatory. It may therefore be called the " nerve cen- 



