638 SCIENCE PROGRESS 



the bulk of fat in a patient the greater will be the absolute 

 amount of chloroform required. It is known that the actual 

 bulk of an individual is the gross weight minus the stored 

 fat ; the presence of this reserve material in anaesthetisation 

 actually subtracts and renders useless some of the chloroform 

 which is administered. 



What may be the actual chemical and physical effect of 

 anaesthetics on protoplasm generally is a difficult problem, and 

 one method which ma}^ be applied to its solution depends 

 upon a study of the differences of potential which may follow 

 the subjection of living nerves to anaesthetic vapour of known 

 strength. N. H. Alcock ^ has extended the work of Waller,^ 

 and, in particular, has investigated the effect of chloroform and 

 ether upon the current of injury which occurs in excised living 

 nerves. A difference of potential existing between the longi- 

 tudinal and transverse section of the nerve slowly declines 

 under normal conditions, but the difference suddenly drops 

 temporarily or permanently according as the vapour is weak 

 or strong (12 per cent, or more). By subjecting certain regions 

 of a nerve to chloroform vapour, it was noticed that an increase 

 of the injury current, roughly proportional to the strength 

 of the anaesthetic, occurred only when the vapour reached 

 the cross section ; applied to the longitudinal surface it caused a 

 decrease. 



The resistance of nerve is not affected by chloroform, 

 and therefore no formation of ions at the expense of the 

 electrolytes in the nerve takes place, but the normal polarisation 

 of the nerve is markedly diminished. 



A very significant fact is noted with regard to the conductivity 

 of nerve before and after chloroform and ether. While the 

 polarisation of the nerve was markedly altered (as Waller had 

 found) there was no change in the electrical conductivity proper. 

 If this is substantiated it would show that no fresh ion forma- 

 tion took place, and that no splitting up of ion-proteid occurred. 

 In a second paper,^ Alcock showed that while there might 

 or might not be a combination of chloroform with the proteid 

 of the frog's skin, the electrical effects could only be accounted 

 for by supposing the existence in the tissues of either membranes 



1 Proc. Royal Soc. vol. Ixxi. p. 264, vol. Ixxiii. p. 166, vol. Ixxvii. p. 267. 

 * Proc. Physiological Soc. November 13, 1897. 

 ^ Proc. Royal Soc, B., vol. Ixxviii. p. 259. 



