_Effect of the pains upon the pulse._ It is curious to observe the effect which a regular pain has upon the rapidity of the mother's pulse; as the former comes on and goes off, so does the other increase or diminish. "The increasing rapidity of the pulse announces the commencement of the pain; it rises and attains its _summum_ with it; and as the pain subsides so does the pulse gradually resume the rate which it had during the intervals; a similar ebb and flow may be heard in the uterine souffle. The more regular the pain is, and the more distinctly it rises to its full extent, the more marked, regular, and distinct, is this change in it. We may also invert the order of things, and say, the more distinctly the rapidity of the pulse comes on and announces the pain, the more regularly it rises and attains a certain height, which it maintains, and then gradually subsides; in like proportion will the pain be more perfect, attain its full extent more completely, and act more efficaciously upon the regular progress of the labour. Where however the rapidity of the beats subsides before it had scarcely begun to increase, the pain is too weak; or where the rapidity rises by sudden starts, the pain is a hurried one; and in either case its effect will be imperfect." (Hohl, _op. cit._ vol. i. p. 108.) In order that we may ascertain these changes correctly, we ought to note the rapidity of the pulse during each successive quarter of a minute as directed by M. Hohl; thus, in a pain which lasts two minutes, the increase and diminution in the rapidity of the pulse may be as follows, 18. 18. 20. 22.; 24. 24. 22. 18. As labour advances it increases, so that shortly before the birth of the child we shall find that what was the rate of the pulse during the height of the pains at the beginning is now the rate of it during the intervals.