RESPIRATION 205 



forth ; whilst at the same time it controls the voice, which 

 is one of the chief means by which the emotions are 

 expressed. That the most diverse causes may induce 

 an attack of asthma is a pathological consequence of the 

 wide ramification of the connections of this centre. 



Not only do constant afferent impulses pour into the 

 respiratory centre from below, it is also under very direct 

 control from the upper regions of the brain. This control 

 is partly unconscious and continuous in nature ; in part 

 it is intermittent and under the dominion of the emotions 

 and will. The nature of the unconscious control is not 

 clearly understood, but when it is withdrawn the centre 

 tends to take on a rhythmical action (Cheyne- Stokes 

 respiration). The voluntary and emotional promptings 

 are no less important, though only intermittently asserted. 

 The exact centre in which such impulses arise has not 

 been localized, but it is probable that it is situated in 

 the cortex. It has been shown, for example, that in 

 cases of hemiplegia there may be partial paralysis or 

 inco-ordination of the respiratory movements on the 

 affected side,* whilst the influence of the emotions on 

 respiration is a commonplace of ordinary observation. 

 We speak, for instance, of ' holding our breath ' in 

 suspense, or of ' gasping ' with astonishment, and so 

 slight are the causes sufficient to set emotional dis- 

 turbances in action that when one wishes to count a 

 patient's respirations it is inadvisable to let him know 

 that one is doing so, or the process is almost sure to be 

 quickened. 



* Grawitz, Zeit. f. Klin. Med., No. 26, and Stirling, ibid., 1896, 

 No. 30, p. 1. 



