ox THE FUNCTIONAL ACTIVITY OF NERVE CELLS. 519 



lactic acid. Lactic acid is more active than oxalic acid. Caustic potash 

 is more active than caustic soda [and potassium salts are more active than 

 sodium salts]. Approximately equal effects are produced by N/50 potash 

 and by N/15 soda. 



§§ 2, 3, and 4. Influence of acids and alkalies, of carbonic acid and of 

 tetanisation, and of temperature, upon electrotonic currents, have formed 

 the chief subject-matter dealt with during the past year. 



Short accounts of these investigations have been given by one of us in 

 the Proceedings of the Physiological and of the Royal Societies ; • and 

 the significance of the results obtained is considered in some detail in the 

 5th and 6th of a series of ' Lectures on Animal Electricity,' delivered at 

 the Royal Institution (advance proofs of which are presented with this 

 Report, together with copies of the papers mentioned in it). A short 

 paper, published in the Proceedings of the Physiological Society, ^ con- 

 cerning the action of CO.2 upon muscle, arose from and is connected with 

 our investigation on nerve. 



The general lines of our inquiry and its results have been as follows : — 



Electrotonic currents are extrapolar effects aroused in living medul- 

 lated nerve. They are assuredly physiological as well as physical, inas- 

 much as they are temporarily suppressed by a rise of temperature to a little 

 above 40°, and by the action of anaesthetic vapours. 



Normally, in frog's nerve, the A current (i.e., on the side of the anode) 

 considerably exceeds the K current (i.e., on the side of the kathode). 

 The ordinary magnitude of A is, to that of K, as 4 or 5 to 1. 



In consequence of a rise of temperature to 40°, the A current is 

 diminished, the K current is increased. In any case the A/K quotient is 

 decreased. In some cases it is reduced below unity, K being greater than A. 



The typical effect of moderate acidification is a diminution of the A 

 current and an augmentation of the K current (diminution of A/K). 



With acidification below the degree termed ' moderate ' the A current 

 may be increased. "With acidification above the degree termed ' moderate ' 

 the K current may be diminished. 



The typical effect of moderate basification is diminution of the Kcurrent. 



It thus appears that the K current is favoured by acidification, dis- 

 favoured by basification, and that alterations of the A current are less 

 uniform and characteristic. 



The effect of prolonged tetanisation upon the K current is similar to 

 that of acidification, viz. the K current is increased. 



The effects of tetanisation upon the A current are less uniform, viz. 

 the A current may be increased, unaltered, or diminished. 



There is a close resemblance between the effects of carbonic acid and 

 those of prolonged tetanisation upon the A and K currents. This resem- 

 blance (which is commented upon in some detail in the 6th of the ' Lec- 

 tures on Animal Electricity ') may be admitted to rank as confirmatory 

 evidence of the principal conclusion previously arrived at from an exami- 

 nation of currents of action, to the effect that ' the tetanisation of isolated 

 nerve gives rise to a production of CO.,.' 



§ 5. Action of ancesthetics and of alkaloids. — The scope of inquiry 

 under this head is very extensive, and we are not yet prepared to give a 



' Action of temperature on electrotonic currents, Proc. Plu/shlog. Soc, November, 

 1896 ; Proc. U.S., December, 1S9G. Action of acids and alkalies on electrotonic 

 currents, Proc. Physiolog. Soc, January, 1897. 



^ Action of CO, on voluntary and on cardiac muscle, Proc. Physiolog. Soc, 

 November, 1896. 



