FUNCTIONS OF MUSCULAR TISSUE. 325 



from their nervous connections with the spinal cord. The muscles of one of 

 the paralyzed limbs were daily exercised by a weak galvanic battery; while 

 those of the other limb were allowed to remain quiescent. This was continued 

 for two months; and at the end of that time, the muscles of the exercised limb 

 retained their original size and firmness, and contracted vigorously, while those 

 of the quiescent limb had shrunk to at least one-half of their former bulk, and 

 presented a marked contrast with those of the exercised limb. The muscles of 

 the quiescent limb still retained their contractility, even at the end of two months; 

 but there can be little doubt that, from their imperfect nutrition, and the pro- 

 gressing changes in their physical structure, this would in no long time have 

 disappeared, had circumstances permitted the prolongation of the experiment." 1 

 This experiment satisfactorily explains the fact observed by Dr. M. Hall, 

 that, in cases in which the cause of the paralysis is situated in the Brain, and in 

 which the Spinal Cord and its nerves are unaffected, the irritability of the mus- 

 cles of the paralyzed part is not destroyed, even after a considerable lapse of time. 

 For, if the capability of performing reflex actions still exist, on the part of the nerv- 

 ous system, it is manifest that the muscles will be occasionally excited to action 

 through this channel; and that their nutrition and vital properties will thereby 

 be preserved, as they were in Dr. Reid's experiments, by the artificial excitement 

 of galvanism. Another equally satisfactory proof that the loss of Irritability, 

 which follows the severance of the connection between the Nervous centres and 

 the Muscle, is not immediately due to the interruption of any influence communi- 

 cated by the former, has been given by the experiments of Dr. J. Ileid (loc. 

 cit.); who found that, if the irritability of Muscles be exhausted by means which 

 have no tendency to impair their healthy nutrition, and the other conditions 

 favor the normal performance of the nutrient processes, the irritability is restored, 

 and remains for some time. His first experiments were on cold-blooded animals, 

 and they would in themselves be sufficiently satisfactory ; but in the Rabbit their 

 subsequent repetition established the fact beyond all doubt. " The sciatic nerve 

 was divided in the Rabbit, and a portion of it removed. One wire from two 

 galvanic batteries consisting of thirty pairs of plates, was applied over the course 

 of the nerve ; and the other wire was applied over the foot, which was kept moist 

 until the muscles had ceased to contract. Three days after this, a weaker battery 

 was used, and the muscles of the limb had recovered their contractility, and 

 contracted powerfully. The more powerful battery was used as before, until 

 the muscles had ceased to respond to the excitement; and three days after this, 

 they had again recovered their contractility." It seems scarcely possible to 

 draw any other inference from these, experiments, than that Irritability is a pro- 

 perty inherent in Muscular tissue, and that the agency of the Nervous system 

 upon it is merely to call it into active operation. 



326. The second doctrine referred to, as having been taught by some Physi- 

 ologists, is, that Muscles, though not dependent on Nerves for their peculiar 

 vital power, are yet dependent upon them for the exercise of that power; all 

 stimuli, which excite muscles to contraction, operating first on the nervous fila- 

 ments which enter muscles, and through them on the muscular fibres. The facts 

 which have been already stated, in regard to the ordinary action of the Muscles 

 of Organic life, furnish a sufficient answer to this hypothesis. It is with great 



1 A fact of an exactly parallel character has fallen under the Author's observation, in 

 a case of Hysteric Paraplegia, in which one leg was occasionally affected with severe 

 cramps. The muscles of this leg suffered much less diminution of size and firmness than 

 those of the other ; so that there was a difference of more than an inch in the circumference 

 of the limbs. But since the paraplegia has been recovered from, voluntary power having 

 been established in both limbs, and the muscles of both having been exercised in the same 

 degree, they have regained their normal size and firmness, and there is no longer any per- 

 ceptible difference between them. 



