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afTigned, and another Sinus is there difcovercd, and 
called the Circular Sinus fubftituted in the room of tbofc 
Receptacles, the fecming PuKation of the Longitudinal 
and Laura! Sinus s aflerctd by many oi the former and 
late Anatomifls, is manileftly by a plain Experiment 
in Vivifedion denied, and the reafon why they appeal 
to beat demonftra? ed ; a new way of the Veins eniering 
the Sinus s, which together with the ftjfufture cf the 
Sinus's themfelvcs, make up a Mechanifm exaflrJy 
adapted to the fer vice of Nature, according totheva* 
rious Pofuions Humane Creatures are at di&rent times 
neceffitated to put themfelves in. 
Chap. y. gives a particular account of tlie Tlexus Cbo- 
roeiJes, whofe original he finds double not before takea 
notice of; He alio difcovers a broad Connexion of both 
branches of thi^ Plesus by the Intervention of the Pia 
Mater ^ ferving to explicate fome difficult Vhanomena in 
Tulpius and iVepfer. Amongft the Glands obferved by 
all in this Plexusy he difcovered feveral Lymph^educ!b, 
by which the enormous Opinions of Willis, Fieujjenimr 
(kc, is rejefted, and their true ufc afTerted. . 
Chap. 8 and 9. He affirms the Rete miralile to be as 
conftantly found in Men as Brutes ; and the reafon of 
its being bigger in Brutes, he looks upon as a provident 
defign of Nature, to hinder the too hafty and copious 
fall of Blood upon the Brain in their prone Pofition, and 
equally hinders its Retroceffion from the Brain, an incon- 
venience to which Man by reafon of his ereft pofture, 
is no ways expofed, and therefore has this Tlexus very 
fmall; and Dogs by their Pofition and manner of feed- 
ing, are not fo expofed to, as Pafture-fscding Creatures 
ire ; fo that in them it is much lefs than in fuch Crea- 
tures yet larger than in Men. To this Vlepcus he makes 
the 
