362 Dr. F. H. Thiele. Efferent Relationship of Optic [Apr. 19, 
Removal of the cerebellar hemispheres by successive sagittal slices without 
previous removal of the tentorium always caused a bilateral extensor rigidity. 
With the removal of only a small portion the rigidity was slight, but with 
the subsequent removals it became much greater. 
When, however, nearly the whole of one cerebellar hemisphere had been 
removed the homolateral rigidity became very much less, but remained in 
full intensity on the contralateral side. When the lesion included Deiter’s 
nucleus the homolateral rigidity completely disappeared, and when the 
mesencephalon was subsequently transected there was no recurrence of 
rigidity on the homolateral side. 
Removal of the vermis and the cerebellar hemispheres by horizontal slices 
caused bilateral extensor rigidity, which remained till Deiter’s nuclei were 
involved in the lesion. Removal of the cerebellum in this way had no 
influence on existing decerebrate rigidity, which, however, became abolished 
when Deiter’s nucleus was destroyed. 
Stimulation of the vermis and the dorsal surface of the cerebellar hemi- 
spheres caused relaxation of the spasm in decerebrate rigidity. The relaxa- 
tion was most marked on the homolateral side. 
The results obtained in this way were exactly the same whether the 
pyramidal tracts had previously been removed by degeneration or not. 
Sections of the superior cerebellar peduncle had only a very slight effect as 
regards rigidity. In this experiment it was always necessary to remove part 
of the tentorium, and no matter how carefully this was performed, a certain 
amount of rigidity supervened. Section of the superior peduncle caused the 
rigidity to become slightly increased. Subsequent mesencephalic transection 
in front of the line of section of the peduncle caused the rigidity to become 
ereatly increased. 
The effects of section of the superior cerebellar peduncles and of piecemeal 
removal of the cerebellar hemispheres on the knee-jerks were also noticed. 
Section of the superior peduncle on one side, directly after emerging from 
the cerebellum, caused the homolateral knee-jerks to become increased. 
Piecemeal removal of the cerebellum by sagittal slices, when about one-third 
of the lateral lobe had been removed, caused in cats an increase in the homo- 
lateral knee-jerk, the contralateral jerk remaining the same or being slightly 
increased. More extensive removal increased the knee-jerks on both sides, 
the homolateral being brisker than the contralateral. Complete removal, 
including Deiter’s nucleus, produced no further change. 
In dogs, piecemeal removal of one cerebellar hemisphere produced the 
same results as obtained by Dr. Risien Russell, namely, increased jerks on 
the homolateral side, diminished on the contralateral. This did not oceur till 
