The  pituitary  membrane  of  the  antrum,  when  in  a  healthy  state,
secretes,  as  we  have  before  stated,  a  transparent,  slightly  viscid  and
inodorous  fluid,  poured  out  only  in  sufficient  quantity  to  lubricate  the
cavity.  But  when  inflammation  is  excited  in  the  membrane,  its  secre-
tions soon  become  more  abundant,  and  are  at  first  thinner,  afterward
thicker  and  more  glutinous.  Their  color  and  consistence  are  not  always
the  same.  Instead  of  being  transparent,  they  sometimes  have  a  dirty,
opacpie  appearance;  at  other  times  they  assume  a  greenish,  whitish,  or
yellowish  color,  and  in  some  instances  they  bear  a  considerable  resem-
blance to  pus,  which,  it  has  been  conjectured,  might  be  owing  to  sup-
puration of  some  of  the  mucous  follicles  and  a  mixture  of  pus  with  it:5
secretions.  Mr.  Thomas  Bell,  however,  inclines  to  the  opinion  that  it
is  attributable  to  an  "alteration  simply"  of  the  secretions  of  the  cavity.
Their  color  and  consistence  are  determined  by  —  the  degree  of  inflam-
mation ;  the  length  of  time  it  has  existed ;  the  state  of  tlie  health  of
the  lining  membrane,  and  that  of  the  surrounding  osseous  walls;  the
egress  which  the  matter  has  from  the  sinus ;  and  the  general  habit  of
the  body.
Affections  of  this  sort  are  more  common  to  young  subjects  than  to
middle-aged  or  persons  in  advanced  life.  An  eminent  French  writer
says  that  of  three  individuals  affected  with  dropsy  (mucous  engorge-
ment j,  the  oldest  was  not  twenty  years  of  age.
