Warren, John. Lectures upon anatomy :.

27 Lect. 2

That the Force of the Heart is not so considerable as some have imagined is plain from this Instance, viz. that in a Child, who soon drops its Navel String, the Cicatriz is then this & yet it does not bleed; but after Death We see by Injections that when the Arteries are full, by pushing on with a little Force, the Navel string will break, which shews, that more Force is used in Injection, than the natural Force of the Heart. The Artery is always full of Blood, only the Column of Blood is sometimes larger & sometimes smaller, as the Heart is in its Systole & Diastole - The Blood sometimes moving with more sometimes with less Velocity, but is always in Motion, it runs with the greatest rapidity ^near to the Heart (because these small Branches all taken together, are larger than the Trunk, as has been said) for the same Reason, that a River at a narrow Part is very rapid, but where wider runs more slowly - This also explains, why an Artery near the Heart bleeds with Interruption, but in small Arteries in a continual Stream, only sometimes quicker & sometimes slower - In an Aneurism, it moves more slowly in the large Part, than in the smaller, where the Motion of the Blood is examined with Glasses, it appears to move faster than it real- ly does, as the Space, which it passes thro' is magnified by the Glasses - Keil computing the Celerity of the Blood, as to ^[?] the Time it takes in moving thro' an Inch of large Artery ^{to be} to the Time

Pulse [?] [?] Description of the [?] Pulses

28 Lect 2

it takes to move thro' a small Capillary, as 100 to 1 - But D^r. Hunter & Haller think it cannot be so great - The Effect of Arteriotomy, besides taking a great Quantity of Blood, Bellini imagined, would be an Increase of it's Motion between the Part opened & the Heart. It is found, to obtain not only there, but also in the neighbouring Parts by lessening the Resistance By Puncturing an Artery, you also occasion a Retrograde Motion as Haller found from the same Cause, & the Blood rushes out from all the adjacent Vessels. Haller was not sensi- ble of any intestine Motion in the Blood, but it seemed to him in his Observations to be going on equably - But he took Notice that the Column of Blood was interrupted in the Arteries, sometimes by Air, which had got in by some Means or other - In the small Arteries however the Blood flows irregularly - Where the small Anastomoses are, the Motion of the Blood is not so well seen, as it sometimes seems to stop & one while to run forward, some have imagined, that Blood Globules have a rotatory Motion on their own Axis, as well as Projectile - A Hard or soft Pulse depends upon the Mate of the Arterial Coats principally, as they are more or less Yielding - The hard Pulse proceeds from Rigidity & Tension. The soft from the Coats being more Yielding & less tense - These are taken great Notice of in the modern Practice near the Crisis of a Fever, when the Solids become relaxed, & the Pulse softer - 1^st. A Large & a small Pulse depend upon the Quantity of Blood thrown out by the Heart

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29 Lect 2

as also do the strong & the Weak on the same Cause, or rather on the Force of the Heart. If the Quantity is great, the Pulse will be large, but a small Pulse will happen, if the Quantity be little - 2^d. On the Coats of the Artery being more or less Yielding, & on more being kept in the Arterial System, depend the slow & quick Pulse, if the Arteries are very Yielding, the Blood will be collected in a greater Quantity in them, & will not so soon be forced into the venal System, hence the Pulse will be fuller. By a quick Pulse in common Language is meant the frequent Action of the Heart. But in Physiology is meant the Time, in which the Stroke is itself given but this is difficult to distinguish - A regular & irregular Pulse depend on the State of the Heart, an Intermittent Pulse is so called, when a Stroke [?] then is mixed, this generally depends on the State of the Artery, which may in some Measure have lost its Elasticity, or on the Weakness of the Heart itself, on which Account the Heart not being able to contract suspends its Action for a Moment, till it receives a fresh Supply of Blood or Animal Spirits, & then renews its Action. Some persons are very sensible of this Intermission from a Struggling or Anxiety of the Heart. M^r. Page was sensible of this, whose Case, we shall have Occasion to mention hereafter. In some Cases, this is an Alarming Circumstance, in others not. Adhesions of the Pericardium or too much Liquor Pericardii may occasion this, or any thing that irritates.