196 



INHIBITION AND BLOOD-PRESSURE. [BOOK i. 



frequency remains the same the force is increased or diminished, the 

 result in both cases is that the pressure is proportionately increased 

 or diminished. This clearly must be the case ; but obviously it is 

 quite possible that the beats might, while more frequent, so lose in 

 force, or while less frequent, so increase in force, that no difference 

 in the mean pressure should result. And this indeed is not 

 unfrequently the case. So much so, that variations in the heart- 

 beat must always be looked upon as a far less important factor of 

 blood-pressure than variations in the peripheral resistance. 



An increase in the quantity of blood ejected at each beat must 

 necessarily augment, and a decrease diminish, the blood-pressure, 

 other things remaining the same. But the quantity sent out 

 at each beat, on the supposition that the ventricle always empties 

 itself at each systole, will depend on the quantity entering into the 

 ventricle during each diastole, and that will be determined by the 

 circumstances not of the heart itself, but of some other part or 

 parts of the body. 



