_— . 
Philosophical Conceptions of Life. 243 
that Hermann is wholly in the wrong and that the muscle- 
currents observed by Du Bois-Reymond really exist in 
healthy muscles. How then shall these currents explain the 
phenomena of muscular contraction? I presume that no 
physiologist of the present day is misled by the superficial 
comparison which Mayer and Amici were led by their micro- 
scopical studies of the muscles of insects to make between 
the striated muscular fibre and a voltaic pile *. But the 
molecular theory by which Du Bois-Reymond has endea- 
voured to explain his natural muscle-currents and their 
negative variation would appear to open up an inexhaustible 
mine of speculative possibilities for those who are inclined to 
speculate. 
Yet the old experiment of Schwann f has always been a 
stumbling-block in the way of any theory that would explain 
muscular contraction by the action of a force which must 
increase inversely as the square of the distance between the 
molecules, for the force of the contraction, as it actually 
occurs, diminishes as the muscle shortens; and hence we find 
so good a physiologist as Radcliffe { reviving in a modified 
form the old hypothesis of Matteucci §, in accordance with 
which the electrical tension of the fibre in the state of rest 
causes a mutual repulsion of the molecules, and so elongates 
the muscle, while the contraction is merely the effect of the 
elasticity of the tissue, which asserts itself so soon as the 
repulsive force is diminished by the negative variation that 
precedes contraction. 
In consequence of these and other difficulties many physio- 
logists are beginning to regard the electrical phenomena as 
subordinate accidents of the chemical processes that go on in 
muscle, and endeavour to explain muscular contraction as 
resulting directly from these chemical processes themselves. 
Arthur Gamgee || has adopted as most probable the chemical 
hypothesis of Hermann {]. This assumes the contraction to 
result from the decomposition of a complex nitrogenous com- 
pound supposed to be contained in the muscular tissue, and 
* Mayer, Miiller’s ‘ Archiv,’ 1854, 8.214; Amici (1858), translation in 
Virchow’s ‘ Archiv,’ Bd. xvi. 1859, S. 414. 
+ Schwann, in Miiller’s Handb. der Phys. 1837, Bd. ii. S. 59. 
¢ C. B. Radcliffe, ‘ Dynamics of Nerve and Muscle’ (London, 1871). 
§ Matteucci, ‘ Lectures on the Physical Phenomena of Living Beings’ 
(translated by J. Pereira), London, 1847, p. 333. 
|| Arthur Gamgee, ‘A Text-Book of the Physical Chemistry of the 
Animal Body,’ vol. i. (London, 1881), p. 418. 
s pe Hermann, ‘Grundriss der Phys. des Menschen,’ 5te Aufl. 1874, 
