and  Circulation  of  the  Blood.
131
After  many  Observations  made  by  Mr.
LEEUWENHoEK  on  the  Blood  of  Cocks,
Sparrows,  Frogs,  Trout,  Perch,  Cod,  Salmon,
&c.  he  affirms,  that  the  red  Particles  in  the
Blood  of  Birds,  Fishes,  and  Water-Animals,
are  constantly  *  flat  and  of  an  oval  Figure,
that  is,  they  are  longer  than  their  Breadth,
and  appear  as  in  Plate  X.  Fig.  V.  The  serous ¬
  Part  of  the  Blood  in  Fishes  and  Aquatic
Animals  is  also  greatly  more,  in  Proportion
to  the  red  Particles,  than  it  is  in  Beasts  or
Men,  and  the  Particles  themselves  are  larger:
so  that,  by  being  bigger,  and  swimming  farther ¬
  asunder,  they  may  be  seen  much  better.
Mr.  LEEUWENHoEK  observed  the  Blood
circulating  in  the  filmy  Wings  of  a  †  Bat,
and  likewise  in  its  Ears,  and  found  the  Globules ¬
  thereof  perfectly  round:  Wherefore,
allowing  his  Assertion,  that  in  Fishes  and
Birds  they  are  always  flat  and  oval,  we  need
no  longer  hesitate  how  to  class  this  odd
Creature;  but,  notwithstanding  its  flying,
ſhall  pronounce  it  to  be  a  Beast.
He  tells  us,  that  Bats  can  see  as  well  by
Day  as  Night:  but  he  supposes  the  Heat
and  Dryness  of  the  Day-Air  would  ſhrivel
up  the  thin  Membranes  of  their  Wings,  and
consequently  stop  the  Circulations  there:
*  Arc.  Nat.  Tom.  I.  Part  II.  p.  51.  Again,  Tom.  II.
Epist.  128.  Again,  Tom.  IV.  Epist.  65.
†  Arc.  Nat.  Tom.  IV.  Epist.  67.
whereas