REPORT ON THE PHYSIOLOGY OP THE NERVOUS SYSTEM. 89 



the soundness of this part of Su" Charles Bell's arrangement, as 

 respects not only the individual nerves thus classed together, but 

 even the general principle on which the entire system rests. 

 The reasoning of Dr. Alison consists, first, in referring the 

 phenomena of natural and excited respiration to the compre- 

 hensive order of sympathetic actions. In these " the pheno- 

 menon observed is, that on an irritation or stimulus being 

 applied to one part of the body, the voluntary muscles of an- 

 other, and often distant part, are thrown into action." Now 

 it has been long since fully established by Dr. Whytt, that 

 these associations in function cannot be referred to any con- 

 nexions, either in origin or in course, of the nerves supplying 

 remote organs so sympathizing; and that a sensatioti is the 

 necessary antecedent of the resulting muscular a«tion. Thus 

 it is known that these actions cease in the state of coma ; 

 are not excited when the mind is strongly impressed by any 

 other sensation or thought ; and that the same muscular con- 

 tractions may be induced by the irritation of different parts of 

 the body, provided the same sensation be excited. Dr. Alison 

 has, however, failed to show* that the essential acts of inspira- 

 tion, viz. the contractions of the diaphragm and intercostals, 

 require the intervention of a sensation. Their continuance in 

 the state of coma, and in the experiments of Legallois and 

 Flourens after the entire removal of the brain, and their di- 

 .stinct reference by these two inquirers to the medulla oblon- 

 gata, which has never been supposed to be the seat of sensa- 

 tion, prove them to be independent of the will and of perception. 

 But this is true only of the essential, not of the associated 

 respiratory phenomena. 



Dr. Alison proceeds to show that there is equal reason for 

 ■classing almost all the nerves of the brain, and many more of 

 the spinal nerves, with those exclusively named respiratory by 

 Sir Charles Bell. Thus the lingual nerve governs an infinite 

 number of motions strictly associated with respiration : the in^ 

 ferior maxillary " moves the muscles of the lower jaw in the 

 action of sucking, — an action clearly instinctive when first per- 

 formed by the infant, frequently repeated voluntarily during 

 life, and always in connexion with the act of respiration." 

 Again, the sensitive branches of the fifth pair cooperate in the 

 act of sneezing. But if these nerves be admitted into the 

 system, the fundamental principle of that system, viz. origin 

 in a line or series, is at once violated. Nor is this connexion 

 in origin more than matter of conjecture, as regards two of the 



* p. 176, and note. 



