5S Dr. J. S. Uitiicn Russell. Experimental [Jan. 25, 



nnd the cerebral hemisphere of the opposite side, and what is its 

 probable nature. 



5. Whether one lateral half of the cerebellum in related mainly to 

 the same side of the spinal cord, to the opposite side, or to both, and 

 what the nature of the relationship is. 



6. What symptoms resulting from experimental lesions of the 

 cerebellum are mostly to be relied on for localisation. 



7. Whether any, and if so which, of the symptoms are dependent 

 on interference with the labyrinth or 8th nerve when experi- 

 mental lesions of the cerebellum are produced. 



The procedures adopted in attempting to elucidate these problems 

 were : 



1. Median vertical section separating the two lateral halves of the 

 cerebellum from each other. 



2. Extirpation of one lateral lobe. 



3. Removal of half the organ, i.e., of one lateral lobe together with 

 one lateral half of the middle lobe. 



4. One or other of the last two methods of procedure as a pre- 

 liminary, and subsequent comparative investigation of the excitability 

 of the two cerebral hemispheres. 



5. Similar preliminary methods as in the last instance, followed 

 by the administration of the essential oil of absinthe, and comparison 

 of the effect of the resulting convulsions on the muscles of the two 

 sides of the body. 



6. Removal of both lateral lobes of the cerebellum. 



7. Extirpation of the whole or half of the posterior part of the 

 middle lobe. 



8. Ablation of the whole organ. 



9. Control experiments on the labyrinth and 8th nerve, which 

 consisted in : 



(o) Extirpation of the labyrinth. 



(6) Intracranial section of the auditory nerve. 



(c) Chemical irritation of the auditory nerve. 



The results detailed refer chiefly to dogs, but the effects of similar 

 lesions of the cerebellum in monkeys are contrasted with these. The 

 question as to whether the cerebellum exerts any trophic influence 

 is separately considered, as is a case of defective development of the 

 cerebellum in a cat. 



The investigation of the excitability of the two cerebral hemi- 

 spheres, as tested by the induced current, yielded results of more 

 than ordinary interest, for, whereas the excitability was equal on the 

 two sides when the cerebellum was intact, the opposite hemisphere 

 was the most excitable after unilateral ablation of the cerebellum, 

 which difference in the excitability persisted, and was still present 



