Philosophical Conceptions of Life. 241 
brilliant series of experiments in animal electricity * is de- 
servedly renowned, that even quiescent living muscles are in 
a state of electrical tension. If, for example, a muscle com- 
posed of parallel longitudinal fibres be exposed with suitable 
precautions, and divided near each extremity by a transverse 
incision, the surface of the muscle will be found to be positive 
to the cut ends, and if one of a pair of non-polarizable elec- 
trodes, connected with a suitable galvanometer, is placed in 
contact with the surface of the muscle and the other in con- 
tact with one of the cut ends, the existence of a current is 
made manifest. The conditions are, moreover, such that while 
the maximum effect is produced when the equator of the sur- 
face is connected with the centre of one of the cut ends, more 
or less current will also be manifested whenever any two 
points of the surface are thus connected with the galvano- 
meter, provided they are not equidistant from the equator. 
In such cases the point most distant from the equator is always 
negative. he electromotive force of this natural current of 
the quiescent muscle varies greatly, but has been found by 
Du Bois-Reymond to amount sometimes to as much as ‘08 
Daniell in one of the thigh-muscles of the frog f. In muscles 
of different form or cut differently from what has just been 
described the currents are somewhat differently arranged ; but 
the example just given must suffice for my present purpose. 
In accordance with the observations of the same investi- 
gator, it is claimed that during a muscular contraction the 
electrical tension diminishes, the normal muscle-current expe- 
riences a negative variation, and this occurs in such a way that, 
as the wave of actual contraction moves along the muscle, 
which it does, according to the observations of Bernstein 
and Hermann f, with a velocity of about 3 metres per second, 
it is preceded by a wave of negative variation. ‘This negative 
variation is indeed so trifling if the muscle contracts but 
once, that it is difficult to observe it; but when the contrac- 
tions succeed each other with great rapidity, as in artificially 
roduced tetanus, it may become sufficient to neutralize com- 
pletely the deflection of the galvanometer due to the current of 
the quiescent muscle. 
But the belief that the electrical currents shown to exist in the 
* Emil Du Bois-Reymond, ‘ Unters. iiber thierische Elektricitat ’ 
(Berlin, 1848-60), and ‘Gesammelte Abhandl. zur allgemeinen Muskel- 
und Nervenphysik’ (Leipsic, 1875-77). 
+ Du Bois-Reymond, Ges. Abhandl. Bd. ii. 8. 243. 
t Bernstein, ‘ Unters. iiber den Erregungsvorgang im Nerven- und Mus- 
kelsysteme’ (Heidelberg, 1871); also Du Bois-Reymond’s ‘ Archiv,’ 
1875, S. 526; Hermann, in Pfliiger’s ‘ Archiv, Bd. x. 1876, S. 48. 
