538 HUMBOLDT AND OTHERS ON LEGALLOls' PAPER. 



It appears also by some of the experiments, that the power of motion in the 

 trunk of the body, is derived from the spinal marrow ; and that, when this 

 organ is partially destroyed, the parts which receive nerves from the destroy- 

 ed portion soon cease to live. By particular management of the spinal 

 marrow, one part of the body can be preserved alive for some time after the 

 other parts are dead. 



These experiments of Dr. Legallois, commenced in 1806, or 1807, were com- 

 municated to the imperial Institute of France, in 1811. The committee of 

 that body, to whom they were referred, namely, Messrs. Humboldl, Halle, 

 and Percy, reported that the experiments had been repeated before them, at 

 three different meetings of several hours each ; and that, to allow themselves 

 sufficient time for reflection, they suffered an interval of a week to take place 

 between the meetings. The committee believe these experiments to have 

 proved, 



1st. That the principle upon which all the movements of inspiration depend, 

 has its seat about that part of the medulla oblongata from which the nerves 

 of the eighth pair arise. 



2nd. That the principle which animates each part of the trunk of the body, 

 is seated in that portion of the spinal marrow from which the nerves of 

 the part arise. 



3d. That the source of the life and strength of the heart is also in the spinal 

 marrow ; not in any distinct portion, but in the whole of it. 



4th. That the great sympathetic nerve is to be considered as originating in 

 the spinal marrow, and that the particular character of this nerve is to place 

 each of the parts to which it is distributed under the immediate influence of 

 the whole nervous power. 



The interesting memoir of Dr. Legallois is confirmed to a certain degree by a 

 communication of B. C. Brodie to the Royal Society of London in 1810, in 

 which are detailed many very interesting experiments, which induced the 

 author to conclude, 



That the influence of the brain is not directly necessary to the action of the 

 heart ; and 



That when the brain is injured or removed, the action of the heart ceases 

 only because respiration is under its influence; and if, under these circum- 

 stances, respiration is artificially produced, the circulation will still continue. 



These various experiments apply particularly to the cases in which the brain is 

 deficient, the effects of mental agitation on the heart are likewise reconcila- 

 ble to the theory which arises out of them. But they throw no light on the 

 question why the motions of the heart are so perfectly free from the influence 

 of the will : and although they seem to prove incostestably that the motion 

 of the heart is independent of the brain, it ought to be remembered that in 

 certain diseased states of the brain, w'here that organ appears to be com- 

 pressed, the action of the heart is often very irregular, and its contractions 

 less frequent than usual. 



— For a later and more accurate account of the functions of respiration, the 

 reader is referred to Dunglison's " Human Physiology, 6th Ed., Phila. 

 1846.— 



END OF VOL. I. 



