508 THE BRAIN. 



respiratory centre, both the power and the stimulus to breathe are at 

 once taken away. No attempt is made at inspiration and there is no 

 appearance of suffering. The animal dies by want of aeration of the 

 blood, which leads after some moments to arrest of the circulation. 



An irregularity in the movements of respiration is accordingly one 

 of the most threatening symptoms in affections of the brain. A sus- 

 pension of the intellectual powers does not necessarily indicate imme- 

 diate danger to life. Even sensation and volition may be impaired 

 without direct injury to the organic functions. Cerebral apoplexy at 

 the surface of the hemispheres, in the lateral ventricles, or in the cerebral 

 ganglia, is seldom immediately fatal, however extensive may be the in- 

 jury of the parts. But when occurring in the substance of the medulla 

 oblongata or its immediate neighborhood, it produces death instan- 

 taneously by the same mechanism as where this part is intentionally 

 destroyed by experiment in the lower animals. When the medulla is 

 beginning to be implicated, in man, by a progressive disease or by 

 gradual failure of the nervous functions, the respiratory movements 

 first affected are those of the nostrils and lips, while those of the chest 

 and abdomen go on for a time as usual. The cheeks are drawn in with 

 every inspiration and puffed out with every expiration, the nostrils 

 sometimes participating in these abnormal movements. A still more 

 threatening symptom, and one which frequently precedes death, is an 

 irregular and hesitating respiration, sometimes noticeable even before 

 the remaining cerebral functions are seriously impaired. These phe- 

 nomena depend on the connection between respiration and the reflex 

 action of the medulla oblongata. 



The process of deglutition is also accomplished under the control of 

 the medulla. Mastication of the food by the movements of the jaws, 

 and its transfer by the tongue to the entrance of the fauces, are volun- 

 tary actions which may be continued or arrested at will. But when the 

 food has passed from the mouth into the pharynx, the act of deglutition, 

 by which it is carried down into the stomach, is reflex and involuntary 

 in character. Once commenced, it cannot be arrested by the influence 

 of the will, as it consists of a series of muscular contractions following 

 each other in regular and undeviating succession. These contractions 

 receive their impulse from the medulla oblongata. In the experiments 

 of Flourens and Longet, fowls and pigeons, after removal of the cerebral 

 hemispheres, never picked up their food spontaneously, nor ever swal- 

 lowed it when placed in the mouth at the end of the beak; but if carried 

 backward and placed in the commencement of the pharynx, it was at 

 once embraced by the muscular walls of this organ, and carried into 

 the stomach by a continuous movement of deglutition. This includes, 

 not only the associated contraction of the walls of the pharynx and 

 oesophagus, but also the stoppage of respiration and the closure of the 

 glottis, by which the food is prevented from passing into the larynx. 

 According to Yulpian, after all parts of the brain have been removed, 

 in cats or guinea pigs, excepting the medulla, swallowing may still be 



