80 THIRD REPORT — 1833. 



from the spinal cord that the heart derives the principle of its 

 life and its motion*. The experimental proof supposed to 

 establish these propositions consisted in destroying in different 

 rabbits portions of the cervical, dorsal and lumbar medulla. 

 Cessation of the heart's action was affirmed to be the constant 

 result of the operation ; but even in some of Legallois's own ex- 

 periments f , the motions of the heart continued after consider- 

 able injury had been inflicted on the spinal cord, and especially 

 on its lower divisions. Still more unequivocal is the evidence 

 that has been advanced by Dr. Wilson Philip, in his Inquiry 

 into the Laws of the Vital Functions. His experiments, which 

 were very numerous and judiciously varied, show that the cir- 

 culation continues long after entire removal of the spinal mar- 

 row, and that by artificially maintaining respiration, the motions 

 of the heart may be almost indefinitely prolonged. Flourens, 

 in the 10th vol. of the Mem. de VAcademieX, ^^'^^ lately con- 

 firmed Dr. Philip's views : he has shown that the circulation is 

 entirely independent of the spinal marrow. The influence ap- 

 parently exerted is only secondary, being due to the suspension 

 of the respiratory movements. Thus all those portions of the 

 spinal marrow which can be destroyed in the different classes 

 of animals without arresting respiration, may be removed with- 

 out aff'ecting the circulation. In fishes and frogs the entire 

 spinal cord may be destroyed without checking the heart's mo- 

 tions, because in these classes the medulla oblongata presides 

 exclusively over the respiratory function. 



Nerves. — The classification of nerves, which is most conve- 

 nient to the physiologist, is based upon their vital properties or 

 functions. Such an arrangement would distribute them into — 

 1, nerves of motion; 2, nerves both of motion and sensation; 

 3, the nerves ministering to the senses of sight, smell and hear- 

 ing ; and 4, the ganglionic system, or, according to Bichat, 

 nerves of organic life. Sir Charles Bell has added a fifth class, 

 comprising nerves which he supposes are dedicated to the 

 respiratory motions. But it will afterwards appear, that the 

 existence of an exclusive system of respiratory nerves is not 

 supported by sufficient evidence. 



The first class of nerves exercising the single office of con- 

 veying motion comprehends the 3rd, 4th, 6th, portio dura of 

 the 7th, the 9th, and perhaps two divisions of the 8th, viz. the 

 glossopharyngeal and spinal accessory. Mr. H. Mayo's expe- 

 riments detailed in his Anatomical and Physiological Commen- 

 taries, No. 1 1 . (and Journal de Physique, tom. iii.) throAv much 



* p. 259. + pp. 100, 101, 105. X p. 625. 



