118 ^The Circulation of the Blood\ 
and the Coats of thefe Veffels are, again, of 
fuch an amazing Thinnefs and Delicacy of 
Contexture, that they are little or no Impe¬ 
diment to our View of the fecret, tho’ regu¬ 
lar, Operations of Nature, and the Laws 
Ihe adts by when tmdifturbed and quiet ” 
whereas our Diffeblions of larger Animals, 
while alive, may (hew her at work, indeed, 
but in fuch Confufion, by our breaking in 
upon her violently, that all her Motions then 
muft be in great Diforder, and confequently 
uncapable of affording any fatisfabtory Infor- 
mation as to the Circulations. 
In this Sort of Creatures too, after view¬ 
ing as long as we think fit the natural and 
regular Current of the Blood, as it is carried 
on in a State of Health; we may, by Pref- 
fare, and feveral other Ways, impede, dif- 
turb, and divert its Courfe; and may find 
Means, by various Mixtures with it, of in¬ 
ducing a morbid State 3 and at laft, by let- 
ting the Creature die before our Glafs, we 
may perceive all the Changes it undergoes, 
and what occafions the intermitting, vibra¬ 
ting, trembling Pulfe of expiring People. 
In feveral of thefe little Creatures we can 
not only fee the general Courfe of the Blood, 
but are able perfe&ly to diftinguifh the 
Figure and Circumfiances of the Globules 
whereof it is compounded, and the Altera¬ 
tions they fuffer when they pafs out of the 
larger into the more minute Veffels. For 
many 
