420 MESSRS. P. GOTCH AND V. HORSLEY 



stimulated. From this it was concluded that the spinal path for those afferent nerve 

 impulses which, proceeding up one sciatic nerve into the cord, subsequently reached 

 the vaso-motor centre, was chiefly contained in the lateral column of the side of the 

 cord opposite the nerve. The experiments of WOROSCHILOFF extended these, and 

 showed that movements of the upper limbs could be only aroused in response to 

 stimulation of the skin of the lower limbs, provided that the lateral columns were 

 intact ; that destruction of the continuity of other portions of the cord did not notably 

 influence the reaction ; that when one lateral column was divided, the skin stimulation 

 on the side of the lesion produced a greater reaction than that on the side opposite 

 the lesion ; and that when the whole cord, with the exception of one lateral column, 

 was divided, the stimulation of the skin on the side of the intact column, produced a 

 much less reaction than did that of the skin on the opposite side. From this last 

 experiment, WOROSCHILOFF assumed that, since the impulses were transmitted from 

 the lower to the upper portion of the cord by the bridge of fibres in the intact lateral 

 column, they travelled throughout along such fibres in one continuous path, keeping 

 entirely to the lateral column. The difficulties involved in this assumption, and the 

 unsatisfactory character of the experiments, are ably set forth in a recent edition of 

 FOSTER'S physiology, to which the reader is referred.* The conclusions, therefore, to 

 which WOROSCHILOFF arrived were that afferent impulses were transmitted entirely 

 by fibres contained in the lateral columns ; and that by far the chief part were trans- 

 mitted by the fibres in the lateral column on the opposite side to the entering nerve. 

 By his first conclusion, he therefore placed both the posterior columns and grey 

 matter out of court, although the former must convey at any rate some impulses 

 since they contain a considerable number of the posterior root fibres, whilst there being 

 no means for the impulses to cross over from the entering roots to the lateral columns 

 of the opposite side, except through the grey matter, this latter is assumed to be in 

 operation by the second conclusion. 



Apart from the contradictions involved in this interpretation of these two sets of 

 experiments, the results remain as definite phenomena. In seeking to ascertain their 

 true meaning, it is essential to realize all the conditions of the experimental procedure. 

 Now, of all these conditions, the one which is the most important is that connected 

 with the experimental necessity of evoking definite reactions. 



These reactions, whether of vaso-motor, convulsive, or other centres, are pro- 

 foundly influenced by anaesthesia. It is certain that in the unanresthetised animal 

 the centres are largely affected by the functional discharge of other centres, and that 

 this influence, although by no means abolished, is diminished by narcosis. In all the 

 experiments of MIESCHER and WOROSCHILOFF no complete anaesthetic was employed, 

 the animals being in MIESCHER'S investigations simply curarised, and in WORO- 

 SCHILOFF'S fixed in a suitable holder. 



* M. FOSTER, ' Text-book of Physiology,' vol. 3, p. 189. Also ' Arbeiten a, d. Physiol. Inst.,' Leipzig, 

 1874. 



