79 



in the case of an excitation of the medulla oblongata, the stopping 

 of the heart is not produced by a loss of irritability of this organ. 



Many cases of syncope are produced by a stopping of the 

 heart's movements in consequence of the influence of an emotion 

 on the medulla oblongata. In these cases it would be of 

 very great importance to excite directly the beatings of the heart, 

 either by compression of the chest or by an application of gal- 

 vanism. 



We ought to say that galvanism applied directly to the heart 

 increases its beatings instead of diminishing them. 



XXIV. ON A SINGULAR DISTURBANCE IN THE VOLUNTARY MOVE- 

 MENTS, APPARENTLY PRODUCED BY AN ACTION OP ATMOSPHERIC 

 AIR ON THE GRAY MATTER OF THE SPINAL CORD, IN BIRDS. 



Some years ago I discovered that after the removal of a large 

 quantity of the gray matter that exists in birds, on the posterior 

 surface of the spinal cord, in the lumbar region, a great disturb- 

 ance took place in the voluntary movements. I attributed this 

 disturbance to the loss of gray matter. I have found, three 

 or four months since, that the same disturbance existed in the 

 voluntary movements after I had merely laid bare the gray 

 matter, and immediately after it had been exposed to the action 

 of air. 



I am perfectly satisfied that it is not in consequence of a 

 mechanical excitation of the spinal cord, accidentally produced 

 during the operation of the removal of the bones and membranes, 

 that this disorder takes place. 



When the spinal cord is laid bare elsewhere than in the region 

 of the lumbar enlargement that is, in any place where the white 

 substance covers completely the gray matter there is no disturb- 

 ance produced in the voluntary movements. 



That disturbance very much resembles the so-called titubn- 

 tion which exists after either the removal of the cerebellum or 

 the section of muscles of the posterior part of the neck. At 

 each movement of progression, the animal tends to fall either 

 forwards, backwards, or laterally. It does not fall completely, 

 but is obliged, in order to avoid falling, to make use of its wings, 

 its tail and its beak. 



