REPORT ON THE PHYSIOLOGY OF THE NERVOUS SYSTEM. 73 



five or six clays old, the larynx was detached from the os hy- 

 oides and the glottis exposed to view. The brain and cere- 

 bellum were then extracted without arresting the inspirations, 

 which were marked by four simultaneous motions,' — a gaping of 

 the lips, an opening of the glottis, the elevation of the ribs, 

 and the contraction of the diaphragm. Legallois next removed 

 the medulla oblongata, when all these motions ceased together. 

 In a second rabbit, instead of extracting at once the entire me- 

 dulla, it was cut away in successive thin slices. The four in- 

 spiratory movements continued after the removal of the three 

 first slices, but ceased after the fourth. It was found that the 

 fourth had reached the origin of the eighth pair of nerves. If, 

 instead of destroying the part in which this motive influence 

 resides, it be simply prevented from communicating with the 

 muscles which are subservient to inspiration, a similar effect 

 ought to be produced. Now it is obvious that the medulla 

 oblongata must transmit its influence to the muscles which 

 raise the ribs, through the medium of the intercostal nerves, 

 and therefore of the spinal marrow, and to the diaphragm 

 through the phrenic nerves, and to these through the spinal 

 marrow. In another rabbit, therefore, the medulla spinalis was 

 cut across about the level of the seventh cervical vertebra. 

 The effect of this operation was to arrest the elevation of the 

 ribs, the other three inspiratory motions still continuing. A 

 second section was made near the first cervical vertebra, and 

 consequently above the origin of the phrenic, with the effect of 

 suspending the contraction of the diaphragm. The par vagum 

 was next divided in the neck, and the opening of the glottis 

 ceased. There remained then, of the four inspiratory move^ 

 ments, only the gaping of the lips, which, however, was suflS- 

 cient to attest that the medulla oblongata still retained the 

 power of producing them all. This power had ceased to call 

 forth the other three motions, only because it no longer had 

 communication with their organs. 



M. Flourens, in a recent memoir already referred to *, has 

 confirmed and extended the views first announced by Legal- 

 lois. He has distinctly traced the comparative action of the 

 medulla spinalis and oblongata, on respiration, in the four classes 

 of vertebrated animals. In birds, he found that all the lumbar 

 and the posterior dorsal medulla might be destroyed without 

 impeding the respiratory function, though it was arrested by 

 removal of the costal medulla. In the mammalia the costal also 



* Memoir cs de V Academie, torn. ix. 1830. 



