[ 323 ] 
different theories have been railed, concerning the 
connection of the lymphatics with the arteries. 
Of thefe, we fhall firft coniider that of the late 
famous profeffor Boerhaave. He obferved, that every 
artery of the body is greater, in its diameter, than 
any of its branches : and this obfervation being found 
true, as far as our eye and the microfcope can inform 
us, he inferred, by analogy, that it held good even 
thro’ the molt minute fubdivilions of the arterial 
fyftem. But, fays he, proportionable to the diameter 
of the canal is the fize of the particles moving thro ! 
it : therefore, if an ultimate capillary artery, admit- 
ting only one red globule at once to pafs thro’ it, fend 
off lateral branches, thefe branches will be capable 
of receiving fuch particles only as are fmaller than a 
red globule. But the particles next in magnitude 
below the red globules are the yellow ferous ones ; 
and the lateral veffel, thus receiving them, is a ferous 
artery, and the trunk of a fecond order of veffels. 
In like manner, this trunk, being continued on thro’ 
many leffening branches, will at laff grow fo minute, 
as to admit only one ferous globule : its lateral 
branches, therefore, will receive only fuch particles 
as are fmaller than the ferous ones : but thefe are the 
particles of the lymph ; and this lateral branch is a 
lymphatic artery, and the trunk of a third order of 
veffels. Thus, in the red arteries are contained all 
the circulated fluids of the body ; in the ferous arte- 
ries, all except the red blood j in the lymphatics, all 
except the red blood and ferum : and this fuboraina- 
tion is, according to the fame la'&vs, continued down 
thro’ fluids more fubtile than the lymph, to the 
fmalleft veffel, which is propagated from the aorta. 
Tt 2 Such 
