i86 



NA TURE 



{Jan. 4, 1872 



ELECTROPHYSIOLOGICA : 



BEr.>JG A\ ATTEMPT TO SHOW HOW ELECI'RICITY MAY DO 

 MUCH OF WHAT IS COMMONLY EELIEVEn m HE THT. 

 SPECIAL WORK OF A VITAL PRIMCrPLE 

 I. 



ON a white marble slab let into the front of a house 

 in the Strada Felice at Bologna is an inscription 

 showing that, in this house, then his temporary dwellin;:;- 

 place, at the beginning of September 1/85, Galvani dis- 

 covered animal electricity in the dead frog, and hailin;^' 

 this event as the well-spring of wonders for all ages (Luigi 

 Galvani in questa casa di sua temporaria diraora al primi di 

 Septembie dell' anno 1786, scoperse dalle morte rane La 

 Kllettricita Animale — Fonte di maraviglie a tutti secoli'. 

 Animal electricity, well spring of wonders for all ages ! 

 Yes, said I, as I copied these words a few weeks ago, and 

 as I went into the house repeating them to myself. Yes, 

 still said I, after seeing what was to be seen within the 

 house. Within the house, indeed, there was much to 

 excite the imagination, and to make me more ready to 

 accept these words as the sober utterance of simple 

 truth. Still the same were the common stairs leading 

 from the open outer door to the landing on the first floor, 

 with its two main doors, one on each side, each one 

 opening to a distinct set of apartments, in one of which 

 had lived the discoverer of animal electricity ; and the 

 only change of moment was one which served to call 

 back more vividly the memorable past— a portrait in 

 lithograph of Galvani himself hanging upon the wall 

 facing the stair-head. Still the same was a third and 

 sm.aller door, at which the portrait seemed to be looking, 

 and beyond which were the stairs leading to the belvedere 

 on the roof so common in Italian houses hereabouts. .Still 

 the same were these stairs, the lower flights of uneven 

 bricks, the upper of ricketty woodwork, unmended, scarcely 

 swept, since the time when Galvani went up and down 

 them afire with the discovery made in the belvedere to 

 which they led. Still the same was the belvedere itself — 

 the same walls, blank on one side, pierced on the three 

 others with arched openings, two at each end, three at the 

 front, each opening being built up breast-high so as to 

 form the parapet— the same roof overhead with its bare 

 rafters and tiles — and, running across each opening a little 

 below its arched top and parallel with the parapet, the 

 very same iron bar upon which the frogs' limbs had been 

 suspended by copper hooks in the experiment to which 

 the inscription on the slab outside the house refers, and 

 about which Galvani wrote : — "Ranasitaque consueto more 

 paratas uncino ferreo earum spinali medulla perforata 

 atquo appensa, septembris initio (1786) die vesperascente 

 supra parapetto horizontaliter collocavimus. Uncinus 

 ferream laminam tangebat ; en motus in rana spontanci, 

 varii, haud infrequentes ! Si digito uncinulum adversus 

 ferream superficiem premeretur, quiescentes e.\citab.antur, 

 et toties ferme quoties hujusmodi pressio adhiberetur.' 

 So little change was there, indeed, that, forgetting the 

 present altogether, I could only think of this experiment 

 in which the existence of animal electricity was divined, and 

 of those myriad other experiments to which it had led, and 

 by which in the end the truth had been made manifest. So 

 absorbed was I in these thoughts that I even forgot to look 

 through the open arches of the belvedere at the blue Italian 

 sky and the other beauties of the prospect. And when at 

 length I came down, I was more than ever in the mind to 

 assent unhesitatingly to the words, " la ellettricita animale, 

 fontedimaravigliea tutti secoli" — more than everconvinced 

 that animal electricity would prove to be the key by which 

 to unlock not a few of the secrets which are supposed to 

 be exclusively in the keeping of life — more than ever re- 

 solved still to go on seeking for truth in the path along 

 which I was urged to go by this conviction. 



Nor was I long at a loss how to begin to carry out this 

 resolution. I wanted to reiterate briefly and more clearly 

 some of the things which I had said before respecting 



animal electricity, and the way in which this force may do 

 a work ascribed to life in muscular action and nervous 

 action ; and at the same time to make use of certain new 

 facts which were not a little calculated to confirm former 

 conclusions. I wanted to show that the same workings 

 of animal electricity may be detected in the condition 

 called tone, and even in growth, and that these 

 processes, no less than muscular action and nervous 

 action, may have to b; looked upon as electrical 

 rather than as vital manifestations. h. natural way 

 of carrying out the resolution I had formed was, in- 

 deed, to do the work ready for me ; and therefore the task 

 I have now set myself is to do this work, beginning with 

 an attempt to set forth a new theory of animal electricity, 

 and then proceeding to say something in turn on the way 

 in which this theory sheds light upon muscular action, 

 nervous action, the maintenance of the state called tone, 

 and the process of growth in cells and certain fibres — ■ 

 something calculated to show that in each of these cases 

 animal electricity may have to do much of what is 

 commonly believed to be the work of a vital principle. 



I. On a theory of animal ckctricity wliich seems to arise 

 iiaiurally out of the facts. 



K current, to which the name of muscle-current is given, 

 may easily be detected in living muscle. It may b2 de- 

 tected by applying the electrodes of the galvanometer, the 

 one to the surface made up of the sides of the fibres, the other 

 to that made up of either one of the two ends of the fibres, 

 and also, though much less clearly, by examining either 

 of these two surfaces singly, provided only the two points 

 to which the electrodes are applied are at unequal 

 distances from the central point of the surface. It may 

 not be detected, if, instead of applying them in this man- 

 ner, the electrodes are applied so as to connect either the 

 two surfaces made up of the ends of the fibres, or two 

 points equidistant from the central point of the surface 

 made up of the sides, or of that formed by either one of the 

 ends of these fibres. A current may or may not be detected 

 under such circumstances, and when it is detected its 

 direction is such as to show that the surface made up of 

 the sides of the fibre is positive in relation to that made 

 up of either one of the two ends, and that the former sur- 

 face is more positive and the latter more negative as the 

 distance increases from the line of junction between these 

 two surfaces. In this way the galvanometer makes known 

 the existence of points of similar and dissimilar electric 

 tension in living muscle ; and the only inference from the 

 facts would seem to be that there is a current when 

 the electrodes are applied so as to bring together 

 points of dissimilar tension, but not otherwise. The facts 

 are not to be questioned. The inferences arising fro.Ti 

 them can scarcely be mistaken. 



This current is to be detected in living muscle, but not 

 in muscle which has passed into the state of rigor mortis. 

 As muscle loses its " irritability," indeed, it ceases to act 

 upon the galvanometer, and no trace of the current is to 

 be met with after the establishment of rigor mortis. As 

 a rule, too, nothing is to be noticed except a gradual failure 

 of current ; but now and then (though not in the frog) 

 there may be a reversal in direction in the last moments 

 preceding the final disappearance. 



When muscle passes from the state of rest into that of 

 action, there is also a change in the muscle current to 

 which the name of " negative variation '' is given by its 

 discoverer Du Bois-Reyinond. Thus, when a gal- 

 vanometer is connected with the gastrocnemius of a frog 

 so as to respond to its muscle-current during the two states 

 of rest and action in the muscle, the needle, which 

 may have stood at 90°, or thereabouts, during the state 

 of rest, is seen to fall back, and take up a position at 5° 

 or nearer still to zero, during action. This change it is 

 which is spoken of as "negative variation." It is a 

 change indicating, not reversal of the current, but simple 

 weakening ; for the idea of reversal, which is readily 



