PRESSURE CONDITIONS IN LUNGS AND THORAX. Q59 



discharges its efferent impulses into the phrenic nerves it also 

 sends impulses by a sort of overflow into the neighboring cardio- 

 inhibitory center. This latter center is, thereby, partially in- 

 hibited, its tonic effect on the heart is diminished, and the rate of 

 the heart is increased. The variability in this factor in different 

 individuals may help to explain the fact that in some cases the 

 rise in blood-pressure occurs during the phase of inspiration, while 

 in others it coincides rather with the expiration. It is observed, 

 at least, that in cases showing an inspiratory rise of pressure there 

 is also a marked inspiratory acceleration of the heart-rate, while 

 in those cases where there is an inspiratory fall of pressure the 

 effect of the inspiration on the heart-rate is absent or small, f 



* Snyder, loc. cii., and Foley, Coblentz, and Snyder, "American Journal 

 of Physiology," 40, 554. 1916. 



