Bauhaus-Universität Weimar

If, however, we reflect that the whole hypothesis of the similarity of the electric 
and the nervous principles is unsupported by any facts, and that, as we have shown 
at pages 513 and 514, these principles differ essentially as to their conductors and in¬ 
sulators, the theory of Prévost and Dumas, and any other modified theory of muscular 
motion as due to electric action, will be perceived to be baseless. 
The muscular fibres certainly appear to become shortened during contraction in the 
intervals of the nervous loops which cross the fasciculi; it is probable, therefore, that 
the parts of the muscle which are traversed by the nervous loops, and which are prin¬ 
cipally exposed to the nervous influence, attract each other, and thus give rise to the 
zigzag inflexion of the muscular fasciculi. 
Dr. Schwann is engaged in performing some experiments with the view of ascertain¬ 
ing whether the contractile force of a muscle diminishes or increases as the contraction 
of the muscle is greater. He employs, in these experiments, the muse, gastrocnemius 
of a frog with a peculiar apparatus. 
In concluding this discussion on muscular contractility, it appears necessary to direct 
attention to the fact that any sudden change in the condition of the nerves of muscles, 
by whatever cause it be produced, is productive of a shock to the muscles. The closing 
or interruption of the galvanic circle, sudden destruction of the nervous tissue, burning, 
chemical influence, mechanical stretching, and all such influences, appear to give an 
impulse to the imponderable principle of the nerves, by which either a current or oscil¬ 
lation of that principle towards the muscle is excited, whether the external influence 
heighten or depress the vital energy of the nerves themselves. Hence muscular con¬ 
tractions may attend any, even the most feeble state of the vital forces, the nervous 
principle being capable of such motion or oscillation as excites the muscles to action, 
when any change is produced in the state of the nerves, even though the activity of 
the nervous principle is upon the point of being annihilated. We have here an oppor¬ 
tunity of verifying the law laid down in the Prolegomena, that excitation is perfectly 
different from augmentation of the vital forces,—that an animal system may be stimu¬ 
lated to death, and that even the narcotic substances (the alterantia nervina), which 
have the property of producing so great a change in the nervous matter, give rise to 
symptoms of irritation or excitation, while they destroy the vital properties of the 
Of the involuntary and the voluntary movements. 
The most obvious distinction which presents itself in classifying the 
different muscular movements, is that between the involuntary and the 
voluntary. On clqser examination, however, this division is found to 
be less natural than it at first appears. It does not agree with the dif¬ 
ferences in the forms of the muscular tissue; and there are many in¬ 
voluntary movements performed by muscles which are subject to the 
will,—movements in some cases following as regular a rhythm as do the 
motions of the heart. Certain muscles also, which are quite independ¬ 
ent of the influence of the will, are nevertheless influenced by particular 
states of the mind; and lastly, the fact that the nerves have as great an 
influence over the involuntary as over the voluntary movements, de¬ 
prives such a classification of much of its interest. The facts stated in a 
preceding page were sufficient to show that a division of muscular move- 


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