562 



NATURE 



{April 17, 1879 



more or less marked, and which present positive instead of nega- 

 tive surfaces tou ards the ends of the fibres. Cold, according to 

 the theory, favours the development of this " parelectronomic 

 layer," 



3. The electrical molecules of a nerve, under the influence of 

 a current which traverses it, assume a new arrangement which 

 consists in their turning negative surfaces towards the positive 

 pole and positive surfaces towards the negative pole. If we con- 

 ceive these molecules as electrically dipolar in the state of rest, 

 they would be arranged in inseparable pairs, the positive pole 

 of each member of a pair being turned to the positive pole of 

 the other, the negative surfaces of the molecules being all turned 

 to the transverse sections ; and the action of the current would 

 consist in an arrangement of all the molecules in the form of a 

 pile. As this rearrangement of the molecules extends in a less 

 degree beyond the portion of nerve traversed by the current, 

 dectrotonic forces are developed. 



Fig. I. 



In Fig. I the upper diagram represents the normal, the lower 

 the electrotonic, arrangement of molecules ; above / are seen 

 the parelectronomic molecules of the natural termination of the 

 fibres. 



4. During stimulation either the electromotive forces of the 

 molecules diminish, or the latter assume a new arrangement, in 

 vrhich they appear less active externally ; but the parelectronomic 

 molecules take no share in these changes. 



The promulgation of this molecular theory aroused many ex- 

 pectations. It appeared probable that the essence of the con- 

 dition of activity and of its conduction in muscle and nerve was 

 connected with the electrical properties of certain particles, rota- 

 tion, oscillation or some other change \a. one particle leading to 

 similar changes in neighbouring particles. Moreover, it appeared 

 conceivable that even the contraction of muscle might be explic- 

 able by the actions of attraction and repulsion among the same 

 particles. 



Although speculation upon the origin of these electro-motive 

 forces in muscle and nerve had hardly taken shape, and although 

 the founder of the molecular theorj' observed a praiseworthy 

 reserve in regard to all such speculation, yet up to the year 1867 it 

 was pretty generally, if tacitly, assumed that the chemical 

 processes occurring in muscles and nerves at rest were essential 

 to the maintenance of the electromotive molecules in constant 

 activity. In a similar way it was taken for granted that excita- 

 tion depended ultimately- upon certain movements of the electro- 

 motive molecules which were, of course, associated in some 

 manner or other with increased consumption of oxygen and 

 increased oxidation. 



Researches which called forth New Virws 



Researches which I made upon the exchanges of the gases and 

 other constituents of muscle ^ furnished me with results which 

 differed materially from the then prevailing conceptions of the 

 functional processes occurring in these organs. I found that 

 muscles contain no oxygen capable of being yielded to a vacuum, 

 and nevertheless that they are capable of prolonged exertion 

 in a medium entirely free from oxygen ; hence I concluded that 

 the chemical process which underlies muscular work is not a 

 process of oxidation, but a process of decomposition, in which, 

 by the saturation of stronger affinities through the passage of 

 atoms into more stable atomic combinations, energy is set free, 

 just as in the alcoholic fermentation of sugar. ^ 



Amongst the products of this decomposition in muscle there 

 occiurs carbonic acid. A comparison of the quantities of carbonic 



I Untersuchungen iiber den Stoffwechsel der Muskeln ausgehend vom 

 Gaswechsel derselben. Berlin, 1867. 



" Similar views have been more recently expressed, and with a somewhat 

 more general application, by J. Liebig, in the " Sitzungsber. der bayr. 

 AiCad.," 1869. ii. 4 : and by Pfluger, " Arch. f. d. ges. Physiol.," x. p. 251, 

 1875. I myself had extended this view to the chemical processes in nerves 

 and glands. 



acid set free during nrascular exertion, and during musail.-.r 

 rigor, showed that in both cases the carbonic acid must spring 

 from the same source, and thus, with the help of an analogous 

 result to which J. Ranke had arrived in the case of lactic acid, a 

 complete analogy between the chemical processes of contraction 

 and of rigor, was found to hold good. Both processes are 

 processes of decomposition, and as products of the decomposi- 

 tion are known carbonic acid, lactic acid, and in the case of 

 rigor an albuminous coagulum discovered by Briicke and Kiihne, 

 which may perhaps in the future be ascertained to be a tran- 

 sitory phenomenon even in the case of contraction. The 

 absorption of oxygen by muscle has nothing to do with this 

 process of decomposition ; the former is related to a synthetical 

 process of restitution in which certain of the products of de- 

 composition are perhaps again utilised. In this way was ex- 

 plained the independence (in point of time) between the absorp 

 tion of oxygen and the production of carbonic acid by muscle. 



According to this conception there occurs, during the con- 

 dition of rest, a perpetual but slow decomposition and a slow 

 process of restitution ; the latter is dependent upon a supply of 

 blood containing oxygen. If the supply be intercepted, then 

 the whole store of decomposable matter within the muscle 

 becomes exhausted, and the muscle passes into rigor. During 

 contraction the process of decomposition is suddenly quickened, 

 and the process of restitution can barely keep pace with it : 

 when the latter lags behind the formQT fatigue results. 



The analogy between contraction and rigor had attracted 

 attention long before, although, excepting the shortening of 

 muscle, no other feature common to the two processes was 

 known. Rigor had been designated as the last contraction of 

 dying muscle. The new conception reversed the comparison, 

 inasmuch as it assimilated contraction to a momentaneous and 

 transitory rigor; and, since then, the physical analogies be- 

 tween contraction and rigor have been discovered to be more 

 and more numerous. It has been found that in rigor as well 

 as in contraction the volume of the muscle diminishes some- 

 what, and that in both processes heat is developed ; while, to 

 • complete the relationship, it has been lately observed that certain 

 evident transitional stages occur between the two.^ Thus stimuli 

 of excessive intensity, when applied to muscle, lead to a condi- 

 tion in which the state of contraction never perfectly disappears, 

 but leaves behind it a residue of shortening. Fatigue and the 

 process of death favour this condition of persistent, rigor-like 

 contraction (Schiff's " Idiomuscular Contraction"), and a 

 similar condition is induced by many muscular poisons, as 

 veratria, delphinia, digitalin, emetin, caffein, &c. 



While pursuing the analogies between the conditions of con- 

 traction and rigor I came upon a view of the nature of animal 

 electricity which differed essentially from that which was then 

 in existence.^ 



Fundamental Conceptions of the Nrw Theory 



The most important and at that time the most certainly ascer- 

 tained fact was this, that a transversely divided muscular fibre 

 exhibits, until it has become completely rigid, a negative poten- 

 tial in the plane of the section, and that this difference of poten- 

 tial diminishes or disappears during the state of functional 

 activity. Having regard to the chemical and physical analogy 

 between the processes of activity and of rigor ; and considering 

 the fact that when an artificial cross-section is made there is 

 from the very first a portion of matter within the fibre which is 

 passing into rigor, I explained this phenomenon on the assump- 

 tion that the process of rigor, like the process of contraction, so 

 modifies the protoplasm that it takes on a lower potential than 

 the unchanged inactive protoplasm. 



If this be so then an artifical cross-section must preserve a 

 lower potential so long as the fibre has not become rigid 

 throughout its entire extent, and on stimulation of the portion 

 yet alive a diminution of the electrical difference must result. 



II._The Electrical Currents of Organs at Rest 



The Absence of Currents in Muscles which are at Rest and 

 Uninjured 



In order to sustain the new theory of animal electricity 

 (which, in opposition to the " Pre-existence Theary ot du 

 Bois-Reymond I have designated the " Alteration Theory ), it 



^ " Arch. f. d. ges. Physiol.," xiii. p. 37^, if76 : fV'- P\='5?. 1878.^^ 

 « "Untersuchungen lur Physiologic der Muskeln und Nerven, . u. 3 

 Heft. Berlin: 1867,1868. 



