284 OF MUSCULAR CONTRACTILITY. 



nious experiments of Dr. J. Reid.* " The spinal nerves were cut across, as 

 *they lie in the lower part of the spinal canal, in four frogs ; and both posterior 

 extremities were thus insulated 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 progressing changes in their physical 

 structure, this would in no long time have disappeared, had circumstances 

 permitted the prolongation of the experiment. "t This experiment satisfactorily 

 explains the fact observed by Dr. M.'Hall, and heretofore adverted to, ( 177, 

 208,) 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 muscles 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 nervous system, it is manifest that the muscles will be con- 

 tinually excited to action through this channel ; and that their nutrition and 

 vital properties will thereby be preserved, as they were in Dr. Reid's experi- 

 ments by the artificial excitement of galvanism. Hence Dr. M. Hall's opinion, 

 that the property of Muscular contractility is derived from the Spinal Cord 

 is no more tenable than that which locates it in the Brain. 



382. The loss of contractility from section of the nerves, takes place more 

 speedily in warm-blooded Vertebrata, all whose vital operations are performed 

 with a much greater activity than in Reptiles and other cold-blooded animals. 

 Dr. Reid found that, in a Rabbit, a portion of whose sciatic nerve had been 

 removed on one side, the muscles of that leg were but very feebly excited to 

 contraction by Galvanism, after the lapse of seven weeks. The change in 

 their nutrition was evident to the eye, and was made equally apparent by the 

 balance. The muscles of the paralyzed limb were much smaller, paler and 

 softer than the corresponding muscles of the opposite leg ; and they scarcely 

 weighed more than half, being only 170 grains, whilst the others were 327 

 grains. It was found, also, that a perceptible difference existed in the size of 

 the bones of the leg, even after so short an interval had elapsed ; the tibia and 

 fibula of the paralyzed limb weighing only 81 grains, whilst those of the sound 

 limb weighed 89 grains. On examining the muscular fibres with the micro- 

 scope, it was found that those of the paralyzed leg were considerably smaller 

 than those of the sound limb, and presented a somewhat shriveled appearance ; 

 and that the longitudinal and transverse striae were much less distinct. 



383. Another equally satisfactory proof, that the loss of Contractility, 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. Reid. It 



* Edinburgh Monthly Journal of Medical Science, May, 1841. 



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

 a case ol 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 cir- 

 cumference of the limbs. But since the paraplegia has been partially recovered from, 

 some degree of voluntary power having been established in both limbs, and the muscles 

 of both having been exercised in the same degree, they have greatly improved in' size 

 and firmness, and there is now little or no perceptible difference between them. 



