but as thefe Dilatations of their Trunks arc caused by the 
refiftance the Blood meets with at thofe Angles of hflebidn 5 
fo thofe Enlargements of them afterwards contribute to re- 
tard the protrufion of the Blood to the Extremities ot thofe 
Arteries : Hence it is, That as the Arteries ot the Pectus 
are not Contorted in fuch Acute Angles as in full grown 
Bodies, fo their Trunks are more Conical, and not here 
and there dilated in divers parts of them, as in the Adult, 
The Trunk of the Splenick Artery has a ftraight progrefs 
in the Fwim and in Infants 5 but in the Adult I have hi- 
therto conftantly found it very much Contorted^ as expreft 
in Fig. 1,25. 
The peculiar Contrivances of the Spernmtick, Arteries of 
^adrupeds as well as Men^ (hew a Conftant defign in Na- 
ture ot taking off that Velocity with which the Blood 
would otherwife pafs thvo tliQ Glands of th^ Tefies: It 
feems to be tor this end that the Tejles of moft Animals- 
(efpecially Men and S^adrupeds ) hang out of the Cavities 
of their Abdomens, that the canals of their Blood Veffels 
may be lengthened : for the Spermatick Arteries (contrary 
to all othersj arife from their Great Trunk, at a far great- 
er diftance from the Tefies than the Arteries of any other 
part of the Body. Nor would the Tefie^ (which are fuch 
neceffary Organs) been thu5 expofed to external Injuries, 
if the end of Nature in lengthening their Blood VeQels had 
not been very confiderable. Befides this lengthening of the 
Spermatick, Arteries^ we find Nature ftill contriving other 
Impediments to check the Current of the Blood in thofe 
Parts 5 it feems for this end that the Spermatic^ Arteries 
are leffen'd at their Original from the Trunk ot Arteria 
Magna in Men, and that the Spermatid^ Arteries of ^tadru' 
peds 2LVQ fo much Contorted hdovQ they reach their Te/?ej. 
The principal Inducement ot Nature in making ufe of 
thefe different Contrivances in the Spermatic^ Arteries of 
Men and ^iadrupeds feems to be^ 
That 
