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TEXT-BOOK OF PHYSIOLOGY 



the cerebellum are attended by such results. The phenomena observed a: 

 many and complex. They differ in extent and character in different anima 

 and in accordance with the extent and location of the lesion, though the no 

 ofjncoordination runs through them all. 



FIG. 257. ATTITUDE ASSUMED AFTER DESTRUCTION OF THE LEFT HALF OF THE CEREBELLUM, 

 (Moral and Doyon, after Thomas.) 



Removal of one lateral half of the cerebellum in the dog is followed by a 

 inability to maintain the equilibrium necessary to the erect position. 

 attempting to stand, the animal at once falls toward the side of the lesion, tt 

 muscles of which at the same time contract and give to the body a distinct! 

 curved condition (Fig. 257). The anterior limbs are extended to theopposil 

 side. On making efforts to regain the standing position, the animal ma 



roll over around the long axis of ft 

 body. Conjugate deviation of th 

 eyes is frequently observed as well a 

 nystagmus. 



After a few days the symptoms pa] 

 tially subside and the animal acquire 

 the power of sitting on the abdome 

 when the anterior limbs are widel 

 extended (Fig. 258). As the daysg 

 by the improvement continues, and th 

 animal recovers the power of walking 

 though each step is attended wit 

 tremor and oscillations of the bod) 

 Any change in the center of gravit 

 such as results^when one leg is lifted may result in a fall toward the side c 

 the lesion, owing to an inability to promptly bring about the necessar 

 compensatory muscle actions. With time the animal continues to improv 

 in its power of adjustment, though it never completely recovers it. Move 

 ments of progression are apt to be characterized by stiffness and accom 

 panied by tremor suggestive of volitional efforts. 



Total removal of the cerebellum is followed by a different train of symp 

 toms. The extensor muscles apparently preponderate in their action, fo 

 the limbs are extended and abducted, the head and neck are retracted, an< 

 opisthotonos is established. In time these effects also partially subside 

 though all attempts at walking are permanently accompanied by tremor am 

 oscillations. The characteristic effect which follows section of the peduncle 

 is again incoordination, manifesting itself in deviation of the head, eyes, in 

 ability to walk, tremor on exertion, etc. The effects vary, however, accordinj 

 to the peduncle divided. Section of the middle peduncle gives rise to th. 



FIG.- 2$%. ATTITUDE IN REPOSE AFTER 

 THE .COMPLETE REMOVAL OF THE CERE- 

 BELLUM BUT DURING THE PERIOD OF RES- 

 TORATION OF FUNCTION. (Morat and Doyon, 

 after Thomas.) 



