1889.] Relation of Physiological Action to Atomic Weight. 21 



December 12, 1889. 



Sir Gl. GABRIEL STOKES, Bart., President, in the Chair. 



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

 for them. 



The following Papers were read : — 



L " The Relation of Physiological Action to Atomic Weight." 

 By Miss H. J . Johnstone, University College, Dundee, and 

 Thos. Carnelley, Professor of Chemistry in the University 

 of Aberdeen. Communicated by Sir Henry Roscoe, F.R.S. 

 Received October 5, 1869. 



II. "An Experimental Investigation into the Arrangement of 

 the Excitable Fibres of the Internal Capsule of the Bonnet 

 Monkey (Macacus sinicus)." By CHARLES E. Beevor, M.D., 

 F.R.C.P., and Victor Horsley, B.S., F.R.S. (From the 

 Laboratory of the Brown Institution). Received December 

 4, 1889. 



(Abstract.) 



After a historical introduction the authors proceed to describe the 

 method of investigation, which was conducted as follows. The 

 animal being narcotised with ether, the internal capsule was exposed 

 by a horizontal section through the hemisphere. By means of com- 

 passes the outlines of the basal ganglia and capsule were accurately 

 transferred to paper ruled with squares of 1 millimetre side, so that 

 a projection of the capsule was thus obtained, divided into bundles of 

 1 millimetre square area. Each of these squares of fibres was then 

 excited by a minimal stimulus, the same being an induced or secondary 

 interrupted current. The movements were recorded and the capsule 

 photographed. 



In all 45 experiments were performed, and they are arranged in 

 eight groups, representing eight successive levels (i.e., from the 

 centrum ovale to the crus) at which the capsule was investigated.. 



Before the results are described in detail a fall account is given of 

 previous investigations, experimental, clinical, and anatomical, on 

 the arrangement of the internal capsule. 



