404 



NATURE 



[August 15, 1907 



and experiment, of which I can offer some evidence. I 

 have tested purified chloroform against the concentrated 

 residue of its impurities, and have found the former to be 

 far more powerful than the latter. And I have compared 

 with each other chloroform or trichlormethane, CHCl,, 

 dichlormethane, CHXl,, nionochlormethane, CH,C1, tetra- 

 chlormethane, CCI.„ as well as manv anesthetics of the 

 ether group, Et,0, EtCl, EtBr, ' Etl, and several 

 ansesthetics belonging to the series of chlorocthanes, 

 members of which have at various times been recom- 

 mended as substitutes for chloroform — e.g., ethylene 

 chloride or " Dutch liquid," CHXl— CH,C1, and ethvl- 

 edene chloride, CHj— CHCL. The conclusion I have 

 drawn from this study is that of all these more or less 

 powerful anesthetics chloroform is the most powerful, the 

 .most certain, the most convenient, and the most trust- 

 worthy. 



But I would repeat the statement that the safe adminis- 

 -tration of chloroform consists in its continuous administra- 

 tion at a strength of betvifeen i and 2 per cent. And if 

 anyone now objects that it may be safe to go up to 3 per 

 cent., or sufficient to go down to \ per cent., I am content 

 to accept the objection as being possibly well founded, 

 because it carries with it the all-important admission that 

 the question of safe anaesthesia is in first instance a ques- 

 tion of quantity, and in second instance a question of 

 idiosyncrasy and of clinical conditions. 



Admitting, then, that the primary condition of the safe 

 administration of chloroform consists in the continuous 

 administration of an atmosphere in which chloroform 

 vapour is between the limits of i and 2 per cent., the 

 question is how best to secure this essential condition. 

 It can be secured by many methods. Given the requisite 

 care, skill, and experience on the part of the administrator, 

 anaesthesia may be properly carried out by any method, 

 empirically or otherwise. But some methods demand more 

 skill and care than other methods, and the task of the 

 ansesthetist may be lightened (or it may be aggravated) 

 by various mechanical appliances. A folded towel drenched 

 with chloroform may be safely used by an anaesthetist 

 whom previous experience has rendered fully alive to the 

 extreme danger of two or three deep inspirations of a 

 concentrated vapour, and whose attention is never dis- 

 tracted from the paramount necessity of " plenty of air " 

 with the " plenty of chloroform." On the other hand, 

 a person unmindful of the physiological elements of chloro- 

 formisation is a dangerous administrator if he is content 

 with the empirical use of any apparatus, however faith- 

 fullv he may carry out the instructions of his instrument 

 maker. 



Methods and apparatus are legion, and it would be 

 futile or invidious on my part to attempt to describe or 

 criticise in detail any one method or apparatus. But 1 

 may usefully invite your consideration of certain prin- 

 ciples and ask you to recognise that for their trial by 

 experiment the chief necessity is a simple method, such 

 as I have just described, enabling us to test percentages 

 quickly. Thus, by the use of this method, Mr. Symcs ' 

 has determined what are the usual percentages of chloro- 

 form vapour offered to inspiration by an ordinary .Skinner's 

 mask, and found them to range between the desirable 

 limits of I and 2 per cent., with occasional fluctuations 

 up (o .about 3 or 4 per cent. 



All apparatus designed for the delivery of chloroform 

 vapour of definite and controllable percentage is based upon 

 one or other of two principles. On the first or vacuum 

 system, of which the best known examples are the 

 apparatus of Snow and that of Harcourt, the patient 

 inspires air through a vessel containing liquid chloroform 

 by a broad inlet tube and a closely fitting face-piece. 



On the second or plenum system, of which the examples 

 best known to me are the apparatus of Dubois and that 

 to which 1 have given the name of the " wick vaporiser," - 

 Ihe patient inspires from a freely open face-piece in which 

 an excess of chloroform and air at required percentage is 

 maintained by a pump. 



In my opinion, if apparatus is to be adopted, the plenum 

 is preferable to the vacuum principle : for in the latter 

 case it is more difficult to secure uniformity of adminis- 



' Svmes, Lancet, July q. 1904. 



■-' Waller, Proc. Physiol. Soc, August 19, 1904. 



NO. IQ72, VOL. 76] 



tration, which requires a perfect fit of the face-piece, still- 

 ness of the chloroform over which the inspired current of 

 air is drawn, and which causes of necessity a considerable 

 added resistance to inspiration. By the plenum system 

 there is a more uniform percentage of supply, and the 

 patient breathes freely from an open loosely fitting face- 

 piece, the cavity of which is kept filled to overflowing by 

 an e.tcess of mixture of controllable strength. 



But, whichever of these two systems be followed, rtie" 

 choice is obviously one that can only be dete.irm\Tied by 

 experience, both clinical and of the labora iry. EquaPr ' 

 obviously the so-called accurate percentag' V afforded by 

 any method can only be appro.ximately acciii .Ce under the 

 sometimes diflicult conditions of practical administration, 

 and it is therefore of principal importance to ascertain by 

 a simple and ready method of estimating percentages such 

 as I have described above what is the degree of accuracy, 

 or, if you prefer to say so, the range of inaccuracy to 

 which any method or apparatus is subject under thp 

 ordinary conditions of its application. 



You may indeed sometimes hear it said that the per- 

 centage can be judged of by the sense of smell, which 

 therefore affords the readiest means of estimating the 

 strength of a mixture, to which I should like to add yes. 

 certainly, provided the observer by previous experience of 

 known percentages has formed some standard of com- 

 parison on which his opinion is based. 



I have finished what I set myself to say to-day concern- 

 ing the physiological problems involved in the question of 

 safe anjesthesia by chloroform. 



But I have reserved for my conclusion certain consider- 

 ations by which it is customary to introduce the particular 

 subject under review. May I briefly trespass further on 

 vour attention lo say something about the conditions under 

 which physiological inquiry is pursued in London? 



Physiology, in the technical and restricted sense 

 commonly received in this country, has become so closely 

 associated in the public mind with vivisection, and, as 

 dealt with in the medical curriculum, is so narrowly re- 

 duced to what is strictly necessary and practicable, that 

 its real scope and value as a general science have been 

 altogether lost sight of. 



I do not propose on the present occasion to deal with 

 the question of vivisection either on its ethical or on its 

 utilitarian aspect. All I wish to do is to bring distinctly 

 before your minds two considerations that may, I hope, 

 contribute to a broader and truer conception of the place 

 of physiology among the sciences, though they assuredly 

 will not justify the claim of Dubois-Reymond that physio- 

 logy is the queen of the sciences. 



The first of these two considerations is that the province 

 of vivisection, essential as it is, is a very narrow and 

 restricted province indeed in the domain of physiology. 

 In the ordinary routine of the physiological laboratory 

 experiments involving vivisection are infinitely less 

 numerous and infinitely less exacting than experiments 

 that involve no vivisection. Vivisection is, in fact, an 

 infinitesimal fraction of experimental physiology, whereas 

 in the minds of many who should know better experi- 

 mental physiology always means vivisection : the two terms 

 are taken as synonymous, and an odium that should not 

 have been attached either to physiology or to vivisection 

 has been directed through vivisection upon the whole ol 

 physiology. Vet do not mistake my meaning. 1 do no* 

 for one moment surrender the claim that upon ethical and 

 utilitarian grounds vivisection is lawful ; I deprecate the 

 perverted picture of vivisection that is presented to public 

 opinion by sensational agitators and the perverted notion 

 of physiology that is one of the evil results of the anti- 

 vivisection crusade. But I do not desire to dwell on the 

 vivisection question ; I do not consider that it can be use- 

 fully considered by the general public without an intimate 

 knowledge of the subject, itself possible only to the 

 specialist. An ordinary normal person who should sav he 

 approved of vivisection would be, in my opinion, even 

 more objectionable than an ordinary normal person w^ho 

 should express a detestation of vivisection, for the bare 

 idea of vivisection is repugnant to every humane person. 

 To bring dispassionate argument against such natural re- 

 pugnance seems to me hardly less mischievous than to 

 fan repugnance into hatred by passionate appeals to the 



