520 REroRT— 1897. 



detailed and systematic report on any given portion of this extensive iield. 

 All that we think desirable at this stage is to offer evidence of the physio- 

 logical character of the electrotonic currents under our study, by showing 

 that these currents are subject to modification by anaesthetic and other 

 drugs. We have selected for this purpose reagents, the effects of which 

 upon the currents of action were most familiar to us, viz. ether, chloro- 

 form, and aconitine.^ 



Electrotonic currents ai'e tem-porarily diminished under the influence 

 of ether (about 50 per cent, vapour in air), jiermanently diminished under 

 the influence of chloroform (about 10 per cent, vapour in air). As regards 

 the expression ' permanently,' it should be remarked that it implies ' during 

 an observation of reasonable length, generally one hour,' for we have more 

 than once observed partial recovery at the end of several hours, and with 

 a new transverse section to the nerve. 



[The question of structural disorganisation of nerve by ether and chloro- 

 form vapour is dealt with in a separate report ("Waller and Lloyd).] 



Aconitine hydrochloride in weak solution (1 in 1,000 saline) gives an 

 augmentation of A and K ; in stronger solution (1 in 100) it gives a 

 gradual diminution ending in abolition of A and K ; in solutions of inter- 

 mediate strength it gives augmentation followed by diminution. In all 

 the experiments upon which these statements are based the nerve was 

 left to soak for one minute in the test-solution. 



V. Histological Changes in Medullated Nerve after Treatment with the 

 Vajjours of Ether and Ch loroform, and with CO^ By A. D. Waller, 

 M.B., F.llS., and F. Seymour Lloyd. 



§ 1. Introductory Note by Dr. Waller. 



The following observations form part of an investigation of the action 

 of anaesthetic vapours on the electro-mobility of isolated nerve. A brief 

 preliminary account of that investigation was given at the Liverpool 

 meetingof the British Association (1896). The following fuller account 

 deals principally with the practical bearings of the investigation. 



The question whether the alterations of electrical response effected by 

 various re-agents depend upon gross and visible alterations of nerve 

 substance presented itself to my mind at the outset of my observations, 

 more especially in connection with the more or less pronounced toxic 

 action of different anissthetics, and has subsequently been urged upon me 

 from several quarters ; together with the question whether the nerves 

 under observation have been really living, and whether their alterations 

 of response in consequence of reagents has not possibly been due to gross 

 physical disorganisation. 



This group of questions may be understood in two senses, one needing 

 only a very brief and clear answer, the other requiring some little reason- 

 ing, and probably further microscopic investigation. The answers I am 

 about to give refer only to nerves submitted to volatile re-agents and to 

 three re-agents in solution, viz. KBr, NaBr, and Aconitine. 



(a) Briefly, there is under the conditions of my observations no visible 

 alteration in structure of the nerve-fibre, but on pi'olonged exposure to 

 reagents there are more or less distinctly visible alterations. Judged by 

 the only sign available, viz., the negative variation the nerves have been 



' The effects of ether, chloroforin, aconitine, kc, upon currents of action are 

 described in ' Brain' 1896, p. 43. Those of the two first-named reagents are also 

 described in the first two ' Lectures on Animal Electricity.' 



