PHILOSOPHICAL SOCIETY OF WASHINGTON. 59 



Da Bois-Reyniond has defended his views with vigor, and sharply 

 criticised, of course, the labors and logic of his assailant. 17 I 

 need not at present express any opinion as to the merits of this 

 voluminous controversy. It is enough for my purpose to indicate 

 the questions at issue as sufficiently important and uncertain to be 

 well worthy of independent experimental criticism. 



Suppose, however, this criticism should result in showing that 

 Hermann is wholly in the wrong, and that the muscle-currents ob- 

 served by Du Bois-Reymond really exist in healthy muscles. How, 

 then, shall these currents explain the phenomena of muscular con- 

 traction? I presume that no physiologist of the present day is 

 misled by the superficial comparison, which Mayer and Amici were 

 led by their microscopical studies of the muscles of insects to make 

 between the striated muscular fibre and a Voltaic pile. 18 But the 

 molecular theory by which Du Bois-Reymond has endeavored to 

 explain his natural muscle-currents and their negative variation 

 would appear to open up an inexhaustible mine of speculative pos- 

 sibilities for those who are inclined to speculate. 



Yet the old experiment of Schwann 19 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 20 

 reviving, in a modified form, the old hypothesis of Matteucci, 21 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 repul- 

 sive force is diminished by the negative variation that precedes 

 contraction. 



In consequence of these and other difficulties many physiologists 

 are beginning to regard the electrical phenomena as subordinate 

 accidents of the chemical processes that go on in muscle, and en- 

 deavor to explain muscular contraction as resulting directly from 

 these chemical processes themselves. Arthur Gamgee 22 has adopted 

 as most probable the chemical hypothesis of Hermann. 23 This 

 assumes the contraction to l'esult from the decomposition of a com- 

 plex nitrogenous compound supposed to be contained in the muscu- 

 lar tissue, and named inogen. During contraction inogen breaks 



