Iviii Journal of Comparative Neurology. 



Median division of the cerebellum into two halves produces enfeeble- 

 ment of all voluntary motions and diminution of muscular tone. Astasia, 

 or the various trembling irregular and uncertain modifications of volun- 

 tary motion, is pronounced and these symptoms are never fully removed. 

 SchifPs and Vulpian's statements that symmetrical lesions have no effect, 

 prove false. The worm was successfully extirpated in four dogs and two 

 monkeys. The atonia, astasia and paresis were most marked in the pos- 

 terior extremity. One complete half of the cerebellum was successfully 

 removed in four dogs and three monkeys. The effect of the irritation 

 consisted in rotation about the longitudinal axis (toward the uninjured 

 side) deviation of the eye and nystagmus toward the uninjured side. 

 Curvature of the spinal column toward the operated side and tonic cramp 

 motions of the fore foot (sometimes also hind foot) of the operated side. 

 Paresis, Atonia and Astasia were present, especially on the operated side. 

 Compensation occurred by learning to modify the opposing muscles not 

 by a substitution of function in brain regions. Trophic disturbances 

 occasionally appeared. 



A nearly complete extirpation of the cerebellum of a dog which 

 lived two years and a half thereafter, is recorded. The irritative pro- 

 cesses lasted ten days and consisted in motor excitement ond tonic cramps 

 of the cervical, dorsal and anterior extremity muscles, clonic motions of 

 posterior extremities and convergence of the eyes. 



Locomotion was not acquired for more than a year, during which 

 time walking and standing (but not swimming) were impossible. A certain 

 amount of ataxia remained permanently. Intelligence, sensation and 

 sexual functions were undisturbed. The asthenia is explained by the 

 supposition that a part of the motor impulse passes through collateral 

 tracts via the cerebellum. The astasia is explained as a result of imper- 

 fect summation of motor impulses ; this uncertainty or trembling disap- 

 pears when the motion is more rapid. Great emphasis is laid on the fact 

 that the cerebellum acts as a whole. The functions of the cerebellum 

 therefore are, (i) intensifying the potential energy of voluntary motion, 

 (2) enhancing the resting tone of muscles, (3) it accelerates the rhythm 

 of motor discharge and fuses into continual discharge. The conclusions 

 of this author are such as find strong confirmation in the histological 

 studies of the writer, who has shown the connection between pes pedun- 

 culi and cerebellum more complete than heretofore supposed. 



In the case of four dogs, one or both sigmoid gyri were extirpated in 



