450 PHYSIOLOGY CHAP. 



displacement of the centre of gravity to one or the other side as 

 it walks, it can recover its equilibrium either by exaggerated 

 abduction or by exaggerated adduction of the fore-leg, propor- 

 tionate to the degree of displacement and the stage of the step at 

 which it occurs, whether at the moment of dropping or raising one 

 or the other fore-limb. The gait of the drunken man, at least in 

 mild intoxication, also results from depression of the energy and 

 tone of the nervous system (Schmiedeberg, Bunge) ; by facilitat- 

 ing the flexion of the limbs under the weight of the body this 

 produces abnormal involuntary lateral displacements of the centre 

 of gravity, which the individual compensates by exaggerated 

 abduction or adduction of the limbs. 



The movements of the decerebellated dog are not indeed the 

 best adapted to the object of preserving equilibrium and recovering 

 it when menaced, with a minimal expenditure of energy. We 

 have seen that the animal with half a cerebellum lifts the limbs of 

 the injured side, particularly the fore -limbs, higher than the 

 normal and stamps them more firmly on the ground. This 

 peculiarity, to which we gave the name of motor dysmetria, and 

 which is well described by the term " hen's gait," is seen on both 

 sides in dogs after removal of the cerebellum. Whatever the 

 explanation of this dysmetria, it undoubtedly expresses an 

 imperfect functioning of the peripheral organs whose task it is to 

 effect compensation, so that the animal wastes part of its energy 

 uselessly. We have already shown how this may be interpreted 

 as the simple effect of atony of the leg-muscles, owing to which 

 there is a too rapid relaxation of the extensors when the flexors 

 are contracting and a too rapid relaxation of the flexors while 

 the extensors are contracting. So long as this hypothesis has not 

 been experimentally disproved, we cannot include dysmetria in the 

 fundamental elementary symptoms of cerebellar deficiency which 

 consist in atonia, asthenia, and astasia. But we shall return 

 later on to this disputed point. 



The cerebellar ataxy of monkeys which have lost both sides 

 of their cerebellum only differs from that of dogs in the more 

 varied form of the compensatory processes, owing to their greater 

 activity. 



During the period in which the monkeys are unable to stand 

 upright, and are compelled by the functional incapacity of their 

 hind-limbs to drag the body along the ground, they can clamber 

 on to the furniture by means of their fore -limbs, which are 

 always less asthenic than the hind. Even long after the operation 

 the monkey is incapable of standing erect and of walking in the 

 vertical position on its hind-legs only, as it not infrequently does 

 under normal conditions. 



Again, the dorsal curvature of the back, due to atony of the 

 extensor muscles of the vertebral column, is more pronounced 



