636  Microscopic  Examination  of  Butters.    { Am-DJe0cU'i.marm' 
slowly.  In  this  case  much  less  extract  is  obtained,  but  this  defect 
can  be  partly  remedied  by  using  double  the  quantity  of  glycerin 
and  water  given  above.  This  will  give  a  distinct  layer  of  fluid  which 
can  be  easily  decanted  from  the  residue.  Care  must  be  taken  to  see 
that  it  is  free  from  solid  particles  of  all  but  the  minutest  size.  Fit- 
teen  minims  of  the  stronger  or  thirty  minims  of  the  weaker  extract 
is  the  quantity  employed  for  each  injection.  The  extract  may  be 
kept  about  seven  days  in  a  well  stoppered  bottle  containing  a  piece 
of  thymol.  After  this  time  its  injection  is  followed  by  some  local 
disturbance,  due  probably  to  incipient  putrefactive  decomposition, 
which  the  thymol  seems  incapable  of  preventing.  Whether  the 
addition  of  any  other  antiseptic,  of  harmless  nature,  would  obviate 
this  effect,  has  not  yet  been  determined. 
MICROSCOPICAL  EXAMINATION  OF  PURE  AND 
UNADULTERATED  BUTTERS.1 
By  Jean  Ferdinand. 
In  a  paper,  read  before  the  Societe  Francaise' d'  Hygiene,  the 
author  points  out  that  under  the  microscope  a  pure  butter  shows 
round,  regular,  fat  cells.  If  this  pure  butter  has  not  been  carefully 
prepared,  we  note,  in  addition,  granular  masses  of  casein  and  albu- 
minous matters,  together  with  occasionally  (especially  as  this  butter 
does  not  keep  well)  the  spores  or  filaments  of  penicillium.  Marga- 
rine (animal  fat),  on  the  other  hand,  shows  under  the  microscope 
crystals,  separate  or  in  groups.  These  crystals  are  very  character- 
istic, and  are  seen  to  much  better  advantage  if  examined  with  polar- 
ized light,  in  which  case  the  crystals  show  up  brilliantly,  whilst  the 
ordinary  fat  cells  are  dark  or  black.  By  using  a  selenite  plate  in  addi- 
tion, the  effect  is  still  more  remarkable — the  crystals  showing  up  of  dif- 
ferent brilliant  colors  (principally  orange  and  red)  upon  a  blue  ground 
work.  Pure  butter,  melted  down  and  allowed  to  cool,  if  examined 
with  a  selenite  plate  and  polarized  light,  shows  largish  cells,  each 
cell  divided  into  four  segments  by  a  black  cross.  Two  of  the  seg- 
ments are  greenish  and  two  are  orange-yellow,  whilst  the  ground- 
work is  violet-blue.  We  have  thus  an  extremely  simple  and  trust- 
worthy method  for  the  examination  of  butters  with  a  view  to  finding 
1  Journal  d' Hygiene,  August;  the  Medical  Chronicle,  October  1892,  p.  43. 
