480- PHYSIOLOGY CHAP. 



the animal presents side-to-side oscillations of the head, which are 

 evidently due to astasia of the muscles of the neck. Both at rest 

 and in walking the animal exhibits rhythmical oscillations of the 

 head from one side to the other similar to the sign a man makes for 

 no. This symptom can be observed for a week, or even a month, 

 but owing to organic compensation it becomes less 1 and eventually 

 disappears. 



(b) Immediately after the more or less complete extirpation 

 of the crus primum a characteristic symptom makes its appear- 

 ance. As the animal lies quiet, or when the trunk is cautiously 

 raised by placing one hand below the thorax, at each mechanical 

 or auditory stimulus the front paw of the side operated on is 

 raised upward and backward to the level of the ear by flexion of 

 the knee. The paw remains rigid for a moment in that position, 

 and then falls gradually, but the same movement recurs after each 

 stimulus. This obviously dynamic or irritative phenomenon, which 

 recalls the military salute, only lasts three to seven days and 

 gradually disappears. When the animal subsequently begins to 

 walk there is seen to be considerable dysmetria in the movements 

 of the fore-limb, which is due to the atonia of the muscles of the 

 limb, and lasts a longer or shorter time according to the extent 

 and depth of the lesion. But these symptoms, too, disappear 

 owing to organic compensation. 



(c) After the localised extirpation of the crus secondum, parti- 

 cularly when the genu by which this lobule is connected with the 

 lobulus paramedianus is also excised, no dynamic phenomena are 

 ever observed, but only simple asthenia of the muscles of the hind- 

 limb on the same side, owing to which the limb readily flexes 

 under the weight of the trunk. When the extirpation includes 

 the two crura of the lobus ansiformis, there is hen's gait, combined 

 with obvious asthenia and atonia of the two limbs on the side 

 operated on, which becomes less and disappears more slowly by 

 compensation. 



(d) The extirpation of the lobulus paramedianus produces 

 rotation on the longitudinal axis, associated with pleurothotonus to 

 the side operated on. According to van Rynberk these dynamic 

 phenomena, in which the musculature of the trunk plays a special 

 part, are not seen after localised extirpation of the lobus para- 

 medianus. When in addition to this lobule the two crura of the 

 lobus ansiformis are excised, the resulting symptoms strongly 

 resemble those of unilateral removal of the whole cerebellum, but 

 they are more perfectly compensated. 



(e) After the isolated extirpation of the anterior part of the 

 lobulus medianus posterior, which van Rynberk termed lobule S 

 from its configuration, no abnormal symptoms appear. When the 

 crus primum is also extirpated the symptoms which this produces 

 are exaggerated, but eventually they are fully compensated. 



