Relations between the Cerebellar and other Centres, Sec. 23 



In all the experiments the excitation was performed before the 

 general tonus was established, as well as after in the instances where 

 the tonus actually occurred. 



(a) Excitation of the left Crusta before General Tonus is established. 

 — When the crusta was stimulated in the absence of tonus there 

 resulted invariably contraction of both the biceps and triceps. 



(b) Excitation of the left Crusta after General Tonus is established. — 

 When the " acerebral " tonus is established. Excitation of the left 

 crusta produced out of the sixteen experiments : — 



In 13 cases contraction of biceps and contraction of triceps. 

 „ 2 „ ,, relaxation „ 



„ 1 „ relaxation ,, contraction ,, 



In his most recent communication* on the subject of antagonistic 

 muscle action, Sherrington states that he has obtained cessation of the 

 " acerebral " triceps tonic contraction by excitation of the crus 

 pyramidal fibres. As he does not state how often he observed this 

 effect, we cannot compare the conditions of the two sets of 

 experiments. 



D. Excitation of the Crusta of the right Crus Cerebri. 



The right crusta was also excited in eight experiments, and it was 

 found that, as a rule, there was evoked contraction in both biceps 

 and triceps, but twice relaxation of the biceps and once of the triceps 

 was observed. 



E. Excitation of the Tegmentum of the left Crus Cerebri. 



The surface of the tegmentum was excited, and an effect upon the 

 biceps and triceps observed when the stimulation was applied to the 

 region of the red nucleus and the locus niger. Excitation of the 

 anterior corpora quadrigemina was without effect. 



In every case in which the left tegmentum was excited it evoked 

 contraction of both biceps and triceps. 



F. Excitation of the Tegmentum of the right Crus Cerebri. 



The right tegmentum, when stimulated in five cases, gave always 

 contraction of both muscles, as a rule, the triceps being in excess of 

 the biceps, but this was reversed on two occasions. 



G. Excitation of the Cerebellum. 



Excitation of the cerebellum produced very constant and sharply 

 marked effects according as to whether the "acerebral" tonus was 



* 'Koy. Soe. Proc.,' January 21, 1897. 



