69 



2d. Although perfectly paralytic in regard to spontaneous motion, 

 the left posterior extremity, that still in connexion with the spinal 

 marrow, moved very energetically when stimulated by pinching the 

 toes with the forceps. 



3d. The right posterior extremity, or that of which the ischiatic 

 neive was divided, was entirely paralytic, both in reference to spon- 

 taneous and excited motions. 



4th. After the lapse of several weeks, whilst the muscular irri- 

 tability of the left posterior extremity was gradually augmented, that 

 of the right was gradually diminished, phenomena observed when 

 the animal was placed in water through which a slight galvanic 

 shock was passed accurately in the direction of the mesial plane. 



5th. Strychnine being now administered, the anterior extremities 

 and the left posterior extremity, or that still in connexion with the 

 spinal marrow, became affected with tetanus ; but the right poste- 

 rior extremity, or that severed from all nervous connexion with the 

 spinal marrow, remained perfectly placid. 



6th. Lastly, the difference in the degree of irritability in the mus- 

 cular fibre of the two limbs was observed, when these were entirely 

 separated from the rest of the animal. 



After this exposition of the results of his experiments, Marshall 

 Hall adds : ** In a word, the muscles of the limb paralyzed by its 

 separation from both cerebrum and spinal marrow, had lost their 

 irritability ; whilst those of the limb separated from its connexion 

 with the cerebrum only, but left in connexion with the spinal mar- 

 row, not only retained their irritability, but probably possessed it in 

 an augmented degree.* 



It is easy to prove that Marshall Hall has been completely mis- 

 led by his experiments. 



It is well known that the more a muscle is excited, the more it 

 contracts. As the degree of irritability is judged by the degree of 

 the contraction, it follows that to know what is the degree of mus- 

 cular irritability we ought to apply the same excitation to the mus- 

 cles we desire to compare. In his experiments with galvanism and 

 with strychnine, Marshall Hall has not done so. He has applied 



* On the diseases and derangements of the nervous system. 1841, p. 

 215. 



