606 



PHYSIOLOGY OF THE BRAIN-STEM 



upon the edge of the basin, one observes that very often it leaps too far or 

 not quite far enough. Again, when it does succeed in reaching the bank it 

 often settles down with a portion of the body projecting over the edge, whereas 

 a normal frog is never content until it has a solid footing under the whole 

 body. The symptoms attending ablation of the cerebellum are therefore not 

 at all striking (Steiner). 



Eemoval of the cerebellum from the green lizard and the turtle produces 

 no perceptible effect (Steiner, Bickel). 



In operations similar to these on the higher vertebrates, it has been noted 

 that no pain is produced unless the medulla or pons is injured. 



Rolando, Magendie and Flourens long ago observed irregularities in the 

 bodily movements following operations on the cerebellum, but they explained 



them in very different ways. By many 

 researches which have been made on 

 this subject since that time, these dis- 

 turbances have been confirmed and 

 their cause more closely analyzed. 



We cannot discuss all of these in- 

 vestigations here, but must be content 

 to consider some of the leading facts 

 brought out by work done within recent 

 years. 



In order to make the phenomena 

 following extirpation of the cerebellum 

 more intelligible, we shall recite, after 

 Luciani, the clinical history of a dog 

 in which, as was ascertained subse- 

 quently by dissection, all but the lower 

 outer portion of the cerebellum had 

 been removed on the left side, while 



only a small, unimportant fragment had been left on the right (Fig. 270). 

 There were three successive operations, but the following description relates 

 only to the phenomena which appeared after the last, performed on the 13th of 

 August, 1883. 



For some time after the operation the animal was unable to right himself, 

 but lay on his back, the vertebral column bent strongly to the left and the fore 

 limbs powerfully extended. This contracture increased and spread to the hind 

 limbs when the animal tried to place his four feet straight on the floor. The 

 animal ate and drank without help when the head was supported against the 

 wall. Thrown into a tank of water he reared up suddenly with head out of 

 the water and fell over backward. But he soon recovered his equilibrium and 

 swam in the normal fashion, his head out of the water. Coming to the edge 

 of the tank and attempting to climb out, he again fell over backward but soon 

 righted himself in the water. Now and then in turning round the head went 

 under, but it was quickly lifted out and the equilibrium recovered. 



About the second week these symptoms began to abate somewhat. When the 

 animal was placed in a standing posture with the four legs abducted so that he 

 was well supported, and was left to himself, he stood for some seconds swaying 

 backward and forward, but the swayings rapidly became too extensive and he fell 



FIG. 270. Almost complete extirpation of 

 the cerebellum of a dog, after Luciani. 



