Hence it follows, that these milky Ducts are destitute of Valves,
otherwise the _Mercury_ and the injected Liquors would have been
obstructed in their Passage. It is indeed observable, that these Canals
are in some Places streighter and narrower than in others, so as to
give some kind of Obstacle to the Injection; this is not to be imputed
to Valves, but to some kind of Hardness peculiar to the Substance of
the Glands, by which the milky Vessels are compressed. From hence
appears the immediate Inosculation of the milky Ducts, with the small
Ramifications of the Arteries, of which these Glands are composed; so
that the arterial Blood propels and deposits its chylous and serous
Particles by gentle Pressure and Impulse in the milky Ducts, without
other Mechanism than bare Straining and Secretion. For the further and
more exact Description of these Ducts, see _Nuck’s Adenographia_.