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



state in the elongation experiments as in the magnetisation experi- 

 ments. The change of length of the wire was magnified and mea- 

 sured by causing a lever, whose arms were in a great ratio, to deflect 

 a mirror which was observed by means of a telescope and scale at a 

 considerable distance. 



The observed change of length was always a contraction. The 

 change of length calculated from the theory of stresses was also 



always a contraction, the preponderating term JH-^ being always 



negative. 



The difference between the observed and calculated contractions 

 was, however, considerable, the theory only accounting for a part of 

 the observed contraction. 



Diagrams are given showing the values of the magnetisation, of 

 the effect of increase of tension on magnetisation, and of the observed 

 and calculated contractions, all as functions of the field H. 



It was found that the difference between the observed and calcu- 

 lated contractions was approximately proportional to the fourth 

 power of the magnetisation, a diagram showing that, if this corrected 

 contraction be represented as a function of I 4 , the points all lie very 

 near a straight line passing through the origin, the deviations being 

 within the limits of experimental error. 



" On the Relations between the Cerebellar and other Centres 

 (namely Cerebral and Spinal) with especial Reference 

 to the Action of Antagonistic Muscles. (Preliminary 

 Account.)" By Max Lowenthal, M.D. (Wiirz.), M.R.C.P., 

 and Victor Horsley, F.R.S., F.R.C.S. Received February 

 8 —Read February 25, 18U7. 



(From the Laboratory of Chemical Pathology in University College, London.) 



The following is a brief summary of certain results wliicli we have 

 obtained in the investigation of the relations prevailing between the 

 cerebellum and other parts of the nervous system, and which we 

 commenced in consequence of an observation made by one of us (L), 

 on the 24th May, 1895. 



This consisted in the observation that when both cerebral hemi- 

 spheres were removed and, as a result, active extension tonus* of 

 the limbs was obtained, excitation (faradic) of the upper surface of 

 the cerebellum caused immediate relaxation of such tonus so long as 



* We venture to propose the term " acerebral " tonus for the phenomenon, to 

 avoid unnecessary periphrasis, and to distinguish it from that observed after re- 

 moval of the cerebellar hemispheres. 



