366 



RESPIRATION 



[CH. XXIV. 



Pembrey and Pitts have recently taken graphic records of this 

 condition in the hibernating dormouse, hedgehog, marmot and bat. 

 In some cases the respiration has the typical Cheyne-Stokes character 



Fia. 333. Cheyne-Stokes respiration in hibernating dormouse. The line marked y gives time in seconds 

 Line 1 gives the tracing of a respiratory group which occurred once every 80 seconds, the tempera- 

 ture of the animal being 11 C. On warming the animal to 13 C. the respiratory groups became 

 more frequent (line 2). On warming the animal still further it awakened, and breathing, at first 

 accompanied by shivering, became continuous. (Pembrey and Pitts.) 



with a gradual waxing and waning (fig. 333). In other cases periods 

 of respiratory activity alternate with periods of apnoea, but all the 

 respiratory efforts are about equal in force. (Biot's respiration.) 



The Effect of Respiration on the Circulation. 



The main effect of respiration on the circulation is shown in the 

 accompanying figure. It will be noticed that the arterial pressure 



FIG. 334. Comparison of blood -pressure curve with curve of intra-thoracic pressure. (To be read from 

 left to right.) a is the curve of blood-pressure with its respiratory undulations, the slower beats 

 on the descent being very marked ; ft is the curve of intra-thoracic pressure obtained by connecting 

 one limb of a manometer with the pleural cavity. Inspiration begins at i and expiration at e. 

 The intra-thoracic pressure rises very rapidly after the cessation of the inspiratory effort, and then 

 slowly falls as the air issues from the chest ; at the beginning of the inspiratory effort the fall 

 becomes more rapid. (M. Foster.) 



rises with inspiration and falls with expiration, but that the two 

 events are not quite synchronous, the rise of pressure beginning a 



