MEDULLA OBLONGATA. 411 



when the organism becomes a living being. Death is noth- 

 ing more than a permanent destruction of so-called vital 

 physiological properties ; and this occurs successively, and 

 at different periods, for different tissues and organs. 



When we see that frogs will live for weeks, and some- 

 times for months, after destruction of the medulla oblongata, 

 and that, in mammals, by keeping up artificial respiration, 

 we can prolong many of the most important functions, as 

 the action of the heart, for hours after decapitation, we can 

 understand the physiological absurdity of the proposition 

 that there is any such thing as a vital point, in the medulla, 

 or in any part of the nervous system. 



Connection of the Medulla Oblongata with Various Re- 

 flex Acts. There are numerous reflex phenomena that are 

 completely under the control of the medulla oblongata as a 

 nerve-centre. Among these are the various acts connected 

 with respiration, as yawning, coughing, crying, sneezing, etc. 

 It also presides over the coordination of the muscles con- 

 cerned in expression, and the act of vomiting. We have seen, 

 in treating of the pneumogastric nerves, that their galvani- 

 zation arrests the action of the heart in diastole, the same 

 result follows galvanization of the medulla at the point of 

 origin of these nerves. 1 In another volume, we have fully 

 discussed the influence of the medulla upon sugar formation 

 in the liver, as illustrated by the beautiful experiments of 

 Bernard, in which he produced diabetes in animals by irri- 

 tating the floor of the fourth ventricle, and the influence of 

 this centre upon the quantity and the composition of the 



There is very little to be said concerning certain ganglia 

 and other parts of the brain that we have not yet considered. 

 The olfactory bulbs, or ganglia, preside over olfaction, and 

 will be treated of fully in connection with the special senses. 



1 See page 225. * See vol. iii., Excretion, pp. 172, 323. 



