Of e'i1tOSTRICHFS
ration of the f~ime Chy Ch , by the divilion, attenuation and mixture of!
thed
parts of the IFJb  wv~icI1 thls continual agitation is cApable of produ-
c i nr.:                                                         -    -
  TI'hefc Affions iwhichl are efiintially n-cceffary for Life,- ahd which
lLmu-f be
porfobrmed in Birds as in tcrneftrial Animals, are there allb perlorm'd by
Ic f.
piration, airlio' withi difereot Organs,; for tho' the Diaphiragme of t hffi
Birds that have it jiuI'c6dous, or at leaft the Mufclc of thle ILungs in
the
()tricch, har fbrn2 Tetifon and Relaxation, by the menans of whllich, tile
Luns and its Bladders are compreft, it has not that Motdon which it has in
terrftirial Animals, by which the Vifzfrra are fomntimes fosic'd upwards,
foin-
times downwards j and the Mufcl sof the lower flenter, by reafbn of their
fmallnefs, cannot cornprefs them but very feebly, becaule that Iallno{ all
the
lower B3 lly is covered with the Sterntim, whofe lize muft be exceeding great,
as it is, to give rifc to the great Mufcles which do draw  the Wing down-
wards; the frc e-cof thcfc Mufcles being unable to anf wer the powertul AEti-
on of fliglt, itt hey were lefs. So tlat this weaknefL of tle- MufLes of
the
lower e'eatr and Diaphragme; mufi be fupply'd in Birds by the Bladders of
the Lun-s, w4ulchi are alternately filied and emptied in their Refpiration:
and the manner of t ieir aating is thus.
   \VWln the rForav is dilated by tile Aaion of the Pedoral Mufcles, the
Air enters into the Lungs, and at the fame time from the Lungs into the Blad-
ders; but it m uit be underftood that it enters only into thofE which are
in-
clofed in tile TJ() a -, becaufe that there is nothing which;, by dilating
the
Bladders contained in the lower Belly, can give occafion to the Air to enter
in; for on the contrary it is then that they thrink, adid that the Air whichi
they cc tnrain re-enters into the Lungs. But when afterwards'the Tkorax is
compreffwd and contrafled, the Air lockt up in the Bladders of the Thorax,
being tlicreiy fqueezed out, one part goes out through the Larynx, the o-
therenters into tile iladders of the lower B elly, and f'WIlls them   at
the
fame inliint that the upper ones are evacuated; and afterwards wIen the
uppe-r Bladders are fiiled by the dilatation of the Tkorax, they do receive,
not
only the outward Air iro' the Larynx, but alfo that of the Il:dders of tile
lower Belly, which are compreled at the fIam  time that the upper ones are
dilated; and thi, happens to thlen, as well by realon that their Coats do
return in o their firit ltate, by the force of their Spring as becauie that
the Vif-
cera, which have been forc'd and compelTffed by ttie dilaca-ion of the Blad-
ders, do in thkir turn force theem,aided by the Mufces of tie lb)wer Belly,nut-
witihftanding their filallnefs. This makes a Reciprocation and Viciffi tude
of
Impulfions~wxhich fupplys the potent Adfion, produced by the great MuRIces
of tieiiver iilIly~in terreffrial Animals. This ALrionof the Bladders, which
ferve for the Relfiration  of Birds, is plainly feen, when t hcy are dificed
alive.  \Ve liave made the Fxperiment thereof in great Birds, as G e!te and
Turkq-Locks, in which having open'd the lowerBelly, witniout hurting the
Bladderw wh ich are there; it was remnarked that %vlitn the T orax was dtref-
fd in the Expiration, the lo ver Bladders did fvell; and that when it was
dilated for lnipiration, they did fhrink.
    This particular inaniier which Birds have in their Refpiration, may be
 explbi;l'd by the beflo.s of Forges, which feem to have been made after
t'ne
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