20 PHYSIOLOGICAL EFFECTS 



resistance which the force experiences in passing from one bone 

 to another. If the diaphragm form part of the circuit, it is 

 immediately thrown into a temporary state of contraction. If a 

 strong shock be passed through this muscle, the sudden contrac- 

 tion will act so violently on the air of the lungs as to occasion a 

 loud and involuntary shout; while a small charge frequently 

 occasions a violent fit of laughter ; persons of great nervous sen- 

 sibility being much more readily affected than others. 



When a small charge is passed through the spine, it instantly 

 deprives the individual of all muscular power, so that if he be 

 standing at the time, he either sinks on his knees, or falls to .the 

 ground. Mr. Singer, a celebrated electrician, " once accidentally 

 received a considerable charge from a battery through the head ; 

 the sensation was that of a violent but universal blow, followed 

 by a transient loss of memory and indistinctness of vision, but no 

 permanent injury ensued." In persons killed by lightning, red 

 streaks are frequently observed on the skin. It is said that 

 marks are often observed, indicating the passage of the electric 

 fluid along the spine. The blood is usually fluid, and the muscles 

 flaccid ; though occasionally rigidity of muscles has been found. 

 It has likewise been observed that the body undergoes, in such 

 cases, rapid putrefaction. 



From these facts it will be seen that electricity produces a 

 paralysing effect when brought to bear upon the centre of the 

 nervous system. But when transmitted to the muscles of a limb, 

 the invariable consequence is their spasmodic contraction ; and 

 this is true even though the member be in a paralytic state. From 

 some recent researches, it is highly probable that the muscles are 

 not directly sensible to the stimulus of electricity, but that they 

 are thrown into convulsive action by the electric fluid, merely 

 because of its traversing the nerves by which they are supplied. 



PHYSIOLOGICAL EFFECTS OF GALVANISM. 



The Galvanic current, when brought to act on the living body, 

 is capable of producing three classes of effects, viz. : 



1 . The production of peculiar sensations 



2. Of muscular contractions 



