ventricle at once, makes it contract at a different time from the right, and not at a due interval from the contraction of the auricles: for this fluttering of the pulse attacks generally in an instant, and often upon a fruitless effort to expel wind from the stomach. When the contractions of the ventricles are once become asynchronous and inharmonious to those of the auricles, it may require some time to rectify this, and especially while there is an impediment to the blood’s motion through the aorta. This disorder may likewise continue through habit and association, and recur perpetually from less and less causes. The intermission of the pulse, considered in the two preceding paragraphs, is often caused by flatulencies, as well as the fluttering of it mentioned in this.
Twelfthly, The motions of the heart remain in their original automatic state more than any other in the body; the reasons of which are, that the common motions are equally associated with every thing, i.e. peculiarly so with nothing; and that very few impressions make changes in the motions of the heart so great and sudden, as to subject it to the ideas of these impressions: however, as great and sudden changes are sometimes brought on by pain, fear, surprise, joy, &c. we seem to have a semi-voluntary power to alter the motion of the heart immediately, by introducing strong ideas, our power of introducing these being semivoluntary: nay, it may be possible for persons in very particular circumstances to acquire still greater degrees of power over the motion of the heart.
The first observation to be made here, is, that common respiration is performed very feebly in new-born children. A slight disposition therefore to alternate action in the diaphragm, and other muscles of respiration, may be sufficient to account for that degree of respiration which takes place in new-born children. It is natural to expect, that respiration in them should be feeble, since they must lean in this, as well as in other things, to their preceding state in utero.
Secondly, That the vigorous impressions from the cold air, the hands of the midwife, &c. may excite the strong respiration and crying which take place upon birth ordinarily, appears from the methods used to make the new-born child respire freely, where it fails to do this in extraordinary cases; such as applying volatiles to the nose, pouring wine into the mouth, swinging it to and fro, &c. All these methods excite the muscles to contraction, by making strong impressions on the neighbouring sensory nerves. They are also very agreeable to the notion of vibrations.
