71G REPORT— 1898. 



determining the rapidity and degree of alteration met with in the nerve 

 cells. 



A paper on the Morbid Anatomy of a case of lead- poisoning will appear 

 in the spring number of ' Brain,' by Dr. Laslett and myself. 



An examination of the various segments of the spinal cord and the 

 corresponding nerves was made, and it was found that certain cells in the 

 anterior horns showed changes comparable with those described after 

 division of an anterior root, and that these altered cells were limited to 

 these segments from which the most degenerated peripheral nerves and 

 anterior roots were derived, the posterior roots being in all cases noi-mal. 



II. On Excitatory Electrical Changes in Nerve. 

 By Francis Gotch, F.R.S., and G. J. Burch, M.A. 



The authors have employed the apparatus described in their previous 

 report, and have succeeded in obtaining photographic records of the 

 movement of the mercurial meniscus of the capillary electrometer due to 

 the electromotive changes produced in nerve in response to a single 

 excitation. The results have been briefly set forth in communications 

 both to the Physiological Society ' and the Royal Society. ^ In these 

 communications it will be seen that the authors have studied the influence 

 of varying conditions of the nerve upon the character of the electrical 

 response as indicated by that of the photographic record. 



The records themselves are suflaciently large to permit the determina- 

 tion of the time relations of the electromotive changes, and thus afford 

 data for the more precise estimation of the characters of the propagated 

 excitatory state constituting the so-called ' nervous impulse.' 



From an analysis of the records it is thus possible to obtain a history 

 of the amount and extent of the change in any one portion of the nerve 

 when the state of excitation reaches this portion, this state having been 

 started in the nerve trunk by a single stimulus. When two contacts on 

 the uninjured nerve are arranged in connection with the instrument, a 

 change of the above chai'acter occurs, first under the proximal contact 

 (i.e. that nearest the seat of excitation), and later under the distal one ; 

 the algebraic sum of the two eflects is a rapid biphasic change indicated 

 in the photographic record by a spike. Each complete change under one 

 contact only is indicated in the record by a sudden rise, followed by a 

 prolonged tail or after effect ; the E.M.F. of the former attaining a 

 maximum of -03 volt with great rapidity, that of the latter a maximum 

 of -003 volt ^J second later. 



Starting with these fundamental characteristics, the authors have 

 examined the influence of the following changes of condition : (1) electro- 

 .lytic changes produced by polarising currents ; (2) persistent electromotive 

 changes produced by localised injury ; (3) local alterations in temperature ; 

 (4) variations in the intensity of the stimulus ; (5) the frequent repetition 

 of the stimulus ; (6) COo gas, &c. The research is now being extended to 

 comprise the electromotive effects produced in mammalian nerves, both 

 peripheral nerve trunks and nerve roots, as also those known to exist in 

 the spinal cord. 



Endeavours are also beinsr made to obtain records of the changes in 

 mixed nerves, roots and cord, evoked by reflex discharge of the central 



' Journal of PTiysiology, vol. xxii. (xxxii.). 

 = Proc. Itoij. Soc, vol. Ixiii. 1898, p. 300. 



