nc^Z;,i^-}<^^^^  ^^^<^i^'od  for  Testing  Digitalis,  Etc.  479 
Fully  grown  apparently  healthy  cats  were  selected.  In  general 
these  were  stray  cats  of  the  city,  and  represented  all  common  breeds 
and  mixtures.  They  were  accurately  weighed,  and  then  anaesthetized 
in  the  following  manner :  The  animal  was  placed  in  a  small  box, 
just  large  enough  to  accommodate  the  body,  with  a  small  circular 
notch  at  the  top  of  one  end  of  a  size  which  would  just  admit  the 
neck.  A  cat  in  the  box  with  the  neck  in  place,  the  sliding  lid  was 
forced  shut  and  held  by  a  peg.  Thus  the  animal  was  unable  to 
withdraw  its  head.  The  anaesthetic  was  then  given  from  a  small 
copper  cone  carrying  on  a  transverse  screen  a  pad  of  cotton  or 
gauze.  A  few  drops  of  chloroform  were  placed  on  the  cotton  at 
the  start  in  order  to  hasten  this  operation.  /\s  soon  as  the  animal 
was  unconscious  this  pad  of  cotton  was  replaced  by  another  upon 
which  only  ether  was  dropped.  The  cat  was  then  tied  on  an  animal 
board  (somewhat  resembling  the  Harvard)  with  back  down,  legs 
outstretched,  and  head  securely  fastened  in  a  holder.  This  board, 
supported  on  legs,  was  made  so  as  to  drain  at  a  point  near  the  lower 
(tail)  end,  under  which  a  receiving  vessel  was  placed.  The  animal 
in  place,  the  femoral  veins  were  dissected  out  and  small  glass  can- 
nulae  inserted.  The  solutions  were  contained  in  burettes,  the  ouabain 
in  one  and  the  digitalis  body  in  the  other,  and  were  conveyed  to  the 
cannulae  by  narrow  catheter  tubing.  The  injection  extended,  as 
near  as  could  be  arranged,  over  a  period  of  ninety  minutes. 
The  Ouabain  Solution. 
Merck's  crystalline  ouabain  was  used.  The  weighing  was  done 
on  an  accurate  chemical  balance,  and  a  stock  solution  i  :  10,000  was 
made  in  a  one  litre  volumetric  flask.  For  use,  samples  were  drawn 
off  with  a  pipette  and  diluted  to  the  strength  i  :  100,000  in  a  narrow 
glass-stoppered  200  c.c.  cylinder.  All  dilutions  were  made  with 
recently  prepared  physiological  salt  solution.  (0.75  per  cent.  NaCl.) 
The  stock  solution  was  kept  in  a  cool  dark  cupboard,  and  in  no  case 
was  used  after  two  weeks  old.  The  solution  for  use  was  made  up  as 
needed. 
After  running  two  preliminary  experimients  to  become  acquainted 
with  the  technic,  a  series  of  twenty-six  experiments  with  ouabain 
was  begun.    The  procedure  and  results  were  as  follows : 
The  weight  of  the  animal  having  been  taken,  the  theoretical 
amount  of  solution  required  was  calculated.    Since  the  lethal  dose 
