On the Mammalian Nervous System. 235 



February 26, 1891. 



Mr. JOHN EVANS, D.C.L., LL.D., Treasurer and Vice-President, 



in the Chair. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



The Croonian Lecture was delivered as follows : 



CROONIAN LECTURE. < k On the Mammalian Nervous System ; 

 its Functions and their Localisation determined by an 

 Electrical Method." By FRANCIS GOTCH, Hon. M.A., 

 Oxford, and VICTOR HORSLEY, F.R.S., B.S., &c. (From the 

 Physiological Laboratory, Oxford.) Received February 26, 

 1891. 



(Abstract.) 



1. Introduction. 



In the ' Proceedings of the Royal Society,' No. 273 (vol. 45, 1889, 

 18), we published a preliminary account of some of the experi- 

 lents of which the results are given in detail in our full paper. 



In that communication we stated that the object of our work then 

 ras to endeavour to ascertain the character of the excitatory pro- 

 3sses occurring in nerve fibres when either directly, i.e., artificially, 

 scited, or when in that state of functional activity which is due to 

 e passages of impulses along them from the central apparatus. The 

 lost important way in which such a method could be applied was, 

 >bviously, one which would involve the investigation of the excita- 

 3ry changes occurring in the fibres of the spinal cord when the 

 jrtex cerebri is stimulated. We must at once assume that the motor 

 }ide of the central nervous system is practically divisible into three 

 ;ments. (1.) Cortical centres. (2.) Efferent (pyramidal tract) 

 Ibres, leading down through the internal capsule, corona radiata, and 

 spinal cord. (3.) Bulbo-spinal centres contained in the medulla and 

 the spinal cord, and forming the well-known nuclei of the cranial and 

 ilso of the spinal motor nerves. 



It had already been determined, both by direct observation and by 

 ie graphic method (1), that certain areas of the cortex were con- 

 xected with definite movements of various parts of the body, and (2) 

 it while the complete discharge of tho cortical apparatus was 



