x THE FORE-BRAIN 585 



As a concrete instance of these effects, we may, according to 

 Munk, describe the symptoms due to total excision of the centre 

 for the tore-limb in the left hemisphere (D, Fig. 296). During 

 the tirst three to five days after the operation these are as 

 follows : 



(a) Loss of appreciation of contact and pressure on the skin of 

 I In' /'i</ht fore-limb. When one of the left extremities or the right 

 hind-limb is lightly touched with the ringer or the point of a 

 needle, the dog reacts at once by slight movements or tries to bite, 

 or, if the prick is deep, draws away its limb from the unpleasant 

 stimulus. When, on the contrary, the skin of the right fore-limb 

 is stimulated in the same way the dog takes no notice ; it only draws 

 the limb back when it is firmly pressed or pricked, and the animal 

 neither looks round nor attempts to bite, showing that the reaction 

 is only reflex. 



(b) Loss of appreciation of the position of the same limb. The 

 fore-limb can lie placed in any abnormal position, it may be adducted, 

 abducted, pulled forward or backward, the dorsum of the foot may 

 be placed on the ground, the several joints flexed or extended ; the 

 dog does not correct its abnormal posture and remains indifferent to 

 it until it begins to walk again. In the case of the other three 

 legs, on the contrary, the animal corrects the abnormal positions 

 promptly. 



(c) Loss of motor representations of the right fore-limb. This 

 limb is capable not only of reflex movements, but also of move- 

 ments associated with those of the other three limbs, as in walking, 

 running, and jumping. But the animal does not understand how 

 to use the limb separately. If it had been taught before the opera- 

 tion to give its right paw when desired, it is only able afterwards 

 to give the left ; it can no longer scratch itself, or hold a bone or 

 piece of meat with its right foot, but only with the left ; if placed 

 on a table with the right leg hanging over the edge, the animal, 

 though aware of the danger of falling, does not draw back its leg 

 for support. 



(d) Loss of tactile representations in the right fore-limb. The 

 operated dog is capable of walking, running, jumping, and of the 

 rhythmical alternation and association of movements in the four 

 limbs ; in a word, the coarse mechanism of the complicated move- 

 ments is preserved, but the finer regulation of these movements 

 is lost in the right fore-limb. When the animal walks it is evident 

 that the movements of this limb are not properly graded either in 

 lifting it or moving it forward, or in planting it on the ground. At 

 times the animal rests on the dorsum of the foot, and easily slips 

 on a smooth surface ; in fact, it cannot use the limb with the same 

 accuracy and precision as the other three legs, owing, says Munk, 

 to lack of tactile representations. 



He defines these disturbances as "psychical paralysis of 



