^"kfrch'mr""'}  Biological  Standardisation  of  Drugs.  loi 
ton  the  cost  would  be  60  cents  for  frogs  shipped  800  to  1000 
miles. 
Reed  and  Vanderkleed's  method  of  assay  is  probably  w:ell 
known  to  you.  I  quote  from  a  recent  article  by  Githens  and 
Vanderkleed.  "  Guinea  pigs  are  first  weighed  and  then  to  one  pig 
is  given  hypodermically  the  standard  minimal  fatal  dose  as  deter- 
mined by  a  large  series  of  experiments  on  guinea  pigs,  to  a  second 
9/10  of  this,  and  to  a  third  ii/io.  If  the  drug  is  of  the  proper 
strength  the  two  pigs  receiving  the  larger  dose  will  die,  the  third 
will  recover.  If  two  pigs  live  the  dose  is  increased  by  tenths 
until  two  die.  If  all  three  die  the  dose  is  reduced  by  tenths  until 
a  pig  lives."  The  cost  of  animals  at  Washington  would  be  not 
less  than  $2.00  and  the  assay  would  take,  I  presume,  about  a 
day.  However,  in  testing  out  this  method  for  myself  the  smallest 
number  of  animals  used  in  an  assay  was  7,  the  largest  number  18, 
the  average  of  the  test  of  8  different  preparations  being  11  which 
would  cost  us  $5.50  per  assay  and  the  time  required  would  be 
extended  to  at  least  two  days.  Further,  certain  animals  survived 
doses  20  per  cent,  larger  than  had  killed  others.  Thus,  4  were 
killed  with  0.5  mgm.  per  gram  body  weight,  3  lived  with  0.6 
mgm.  doses  of  the  same  drug. 
Hatcher's  method  is  the  most  complex  of  all  although  he  sug- 
gests that  the  retail  pharmacist  would  find  it  available  for  his  use 
on  account  of  its  simplicity.  That  certainly  will  make  it  appear 
attractive  even  though  it  is  undoubedly  the  most  difficult  of  all 
the  American  methods. 
In  this  method  a  cat  is  anaesthetized,  the  femoral  vein  is  ex- 
posed and  a  cannula  introduced.  Then  into  this  the  digitalis 
preparation  is  slowly  injected  and  the  injection  stopped  or  con- 
tinued slowly  when  toxic  symptoms  such  as  irregularity  of  the 
heart  and  respiration,  convulsions,  etc.  are  seen ;  the  end  reaction 
is  the  death  of  the  animal. 
A  modification  of  this  method  is  to  inject  about  75  per  cent, 
of  the  supposed  fatal  dose  which  is  followed  by  the  injection  of 
ouabain  which  acts  like  digitalis  but  more  rapidly  until  toxic  symp- 
toms appear,  the  drug  is  then  continued  more  slowly  until  death 
results.  P^or  this  method  an  accuracy  of  within  3  per  cent,  has  been 
claimed,  but  from  later  investigations  Hatcher  says  a  number  of 
cats  have  been  found  which  tolerate  doses  nearly  50  per  cent,  more 
