88 THE SIGNS OF LIFE [LECT. 



point B, so I compensate B C, then excite through A B, and then 

 lead off B C to the galvanometer, as shown in Fig. 33. You 

 note the deflection. I repeat the experiment with excitation 

 in the reverse direction ; again you note the deflection. I 

 repeat a similar pair of trials upon another point A, merely 

 to get a further pair of observations compensating A C, ex- 

 citing through A B, and leading off through 

 A C. You have noted the deflections, 

 both the B C deflections to your left, and 

 the A C deflections to your right, thus : 

 signifying as you will easily verify in 

 all four instances that the after-effect at 

 A or at B, whether anode or kathode of 

 the exciting current, has been outgoing. 



Repeating a similar series of four trials with an apple a 

 living apple of course and noting the deflections as before, 

 you find that they are in every case 



the other way round, viz., both B C deflec- EOCC-. B C A 

 tions to your right, both A C deflections Resp: 

 to your left, like this : 

 signifying in all four instances that the after- 

 effect at A or at B, whether anode or kathode 

 of the exciting current, has been ingoing. 



Now, is not this an interesting result, 

 and does it not come out very clearly on this system of 

 notation? In my first attempts to examine one of two stimu- 

 lated points by conjoining it through the galvanometer with a 

 third indifferent point, I found it very troublesome to take 

 notes correctly, very difficult to read notes when taken, and 

 quite impossible to realise during an observation, what was 

 the meaning of each individual deflection. But since I have 

 followed and become familiar with this system of notation, all 

 these drawbacks have disappeared, and we may read and 

 compare at a glance " formulae of response " of a great variety 

 of living things. 



I shall not enter into further explanations now ; the method 

 will be used again, and more fully explained in a future lecture, 

 and then appreciated by you as a simplification, if meanwhile 



