ANIMAL ELECTRICITY. LECTURF: IIL 57 



I recollect that the experiment of which you saw the 

 record last week (fig. i6, plate 674) was made upon a 

 fresh nerve immediately after his departure. 



Later in the day the failure (which was the first I 

 had met with) came under discussion. Clearly this 

 nerve had been very much altered in its disposition 

 towards carbonic acid. A reducing action of the sur- 

 rounding muscles must have been at work ; CO. of 

 course. But has this been only muscle CO^ or also 

 nerve CO^ ? Who shall decide and how ? That 

 question must wait, but the obvious question w^hether 

 exaggerated activity of nerve is or is not attended with 

 an increased production of CO^ can be tested at once, 

 since the nerve itself is such a delicate reagent to its 

 presence from outside. A little expired air, acting on 

 the nerve by reason of a quantity of CO^ much below 

 what can be detected by orthodox chemical tests, pro- 

 duces a great change of the galvanometric response 

 (see fig. 18) ; surely if any change takes place within 

 tetanised nerve, if one single molecule of CO, is pro- 

 duced within it, we shall have the characteristic altera- 

 tion of response. Let us do this : take say five 

 normal responses, then tetanise the nerve continuously 

 for five minutes, then take some more responses. If 

 one single molecule of CO^ is evolved within the nerve, 

 we shall have an augmented response, diminishing 

 minute by minute with the disappearance of CO2. 



A blackboard sketch (fig. 20) accompanied this 

 rather extravagantly expressed argument, and the slope 



