22 Dr. M. Lowenthal and Prof. V. Horsley. On the 



trodes, 2 mm. apart. The induction coils used were, one on 

 Kronecker's pattern, the other by the Cambridge Scientific Instru- 

 ment Company. 



History of Previous Observations. 



The history of previous investigation of the relations of the cere- 

 bellum to the other regions of the central nervous system we intend 

 to discuss in a future communication, which will contain the full 

 details of our experiments. 



Synopsis of Results* 



A. Excitation of the Left "Motor" Cortex, i.e., Forelimb Area of the 

 Sigmoid Gyrus of the Left Hemisphere. 



In the dog and cat excitation of the forelimb area of the excitable 

 cortex produced out of fourteen experiments invariably synchronous 

 contraction of both biceps and triceps muscles. The degree of con- 

 traction also was remarkably symmetrical, and in the majority of 

 cases even the relative degree of tonus and clonus respectively was 

 constant. 



Further, when quasi-purposive reflex (?) movements occurred 

 during alterations in the anaesthesia, &c, this symmetry was even 

 more pronounced. 



So far as antagonism is concerned, when the cortex alone was 

 excited, no relaxation of either the biceps or triceps was observed. 

 It will be remembered that these results are purely those obtained 

 from carnivorous animals. 



B. Excitation of the Left Corona Badiata. 



Stimulation of the corona radiata produced in eight cases inva- 

 riably symmetrical and synchronous contraction of both biceps and 

 triceps. This was . an absolutely constant result in all the cases 

 examined. No relaxation was ever obtained. 



C. Excitation of the Cfusta of the Left Cms Cerebri. 



In sixteen experiments the crura were excited on the cut surface. 

 The excision of the cerebral hemispheres was always performed by 

 ligaturing both common carotid arteries, and then dividing the 

 mesencephalon by a single incision passing through, or just in front 

 of, the anterior corpora quadrigemina. 



* It is to be remembered that the muscles prepared for graphic record were in 

 all experiments the biceps and brachialis anticus and the triceps, of the right side 

 only. 



