118 SENSATIONS. 



it is not liable to the same objections as the former. Simple inspec- 

 tion, however, of a nerve at once exhibits, that it is incapable of being 

 thrown into vibrations. It is soft ; never tense ; always pressed upon 

 in its course ; and, as it consists of filaments destined for very differ- 

 ent functions, sensation, voluntary and involuntary motion, &c. we 

 cannot conceive how one of these filaments can be thrown into vibra- 

 tion without the effect being extended laterally to others ; and great 

 confusion being thus induced. The view of Dr. James Stark 1 in regard 

 to the structure of the tubes of the nerves, has led him to adopt a 

 modification of the theory of vibrations. Believing, that the matter 

 which fills the tubes is of an oily nature, and as oily substances are 

 known to be non-conductors of electricity ; and farther, as the nerves have 

 been shown by the experiments of Bischoff to be amongst the worst 

 possible conductors of electricity, he contends, that the nervous 

 energy can be neither electricity nor galvanism, nor any property re- 

 lated to them ; and he conceives, that the phenomena are best explained 

 on the hypothesis of undulations or vibrations propagated along the 

 course of the tubes by the oily globules they contain. 



3. The last hypothesis is of later date, subsequent to the disco- 

 veries in animal electricity. The rapidity with which sensation and 

 volition are communicated along the nerves, could not fail to suggest a 

 resemblance to the mode in which, the electric and galvanic fluids fly 

 along conducting wires. Yet the great support of the opinion was in 

 the experiments of Dr. Wilson Philip 2 and others, from which it ap- 

 peared, that if the nerve proceeding to a part be destroyed, and the 

 secretion, which ordinarily takes place in the part be thus arrested, 

 the secretion may be restored by causing the galvanic fluid to pass 

 from one divided extremity of the nerve to the other. The experi- 

 ments, connected with secretion, will be noticed more at length here- 

 after. It will likewise be shown, that in the effect of galvanism upon 

 the muscles, there is a like analogy ; that the muscles may be made 

 to contract for a length of time after the death of the animal, and 

 even when a limb is removed from the body, on the application of the 

 galvanic stimulus; whilst comparative anatomy exhibits to us great 

 development of nervous structure in electrical animals, which astonish 

 us by the intensity of the electric shocks they are capable of commu- 

 nicating. 



Physiologists of the present day generally, we think, accord with 

 the electrical hypothesis. The late Dr. Young, 3 so celebrated for his 

 knowledge in numerous departments of science, adopted it prior to 

 the interesting experiments of Dr. Philip ; and Mr. Abernethy, 4 whilst 

 he is strongly opposing the doctrines of materialism, goes so far as 

 to consider some subtile fluid not merely as the agent of nervous 

 transmission, but as forming the essence of life itself. By putting a 

 ligature, however, around a nervous trunk, its functions, as a con- 

 ductor of nervous influence, are paralyzed, whilst it is still capable 



1 Proceedings of the Royal Society, No. 56, Lond., 1843. 



2 Philosoph. Trans, for 1815, and Lond. Med. Gazette for March 18, and March 25, 1837. 



3 Med. Literature, p. 93. Lond., 1813. 



4 Physiological Lectures, exhibiting a view of Mr. Hunter's Physiology, &c. Lond., 1817 . 



