'^Sptember!'^9*2oJ  United  States  Pharmacopoeial  Revision.  649 
withdrawn  and  the  saphenous  vein  clamped  with  a  bulldog  clamp 
The  preparation  thus  injected  is  entirely  carried  into  the  circulation 
by  means  of  the  main  current  of  blood  in  the  femoral  vein. 
The  "checking  of  an  assay  by  making  injections  of  the  sample  and 
of  the  standard  into  opposite  sides  from  the  first  used  is  no  check 
except  in  so  far  as  it  checks  conditions  on  the  two  sides  of  the  dog. 
This  featme  can  better  be  eliminated  by  using  only  one  side.  Fur- 
ther, by  the  official  method,  if  it  is  impossible  to  complete  the  test 
and  the  check  on  a  dog,  no  option  is  left,  but  to  repeat  both  test 
and  check  on  another  dog.  It  is  occasionally  necessary  to  check 
an  assay  on  a  second  dog  when  conditions  during  the  first  test  were 
unfavorable  to  accuracy  but  no  advantage  results  from  a  retest  on 
the  same  dog." 
Pituitary  Extracts. — ^We  strongly  recommend  that  the  Isolated 
Uterus  method  be  retained  as  the  ofiicial  method  for  testing  Liquor 
Hypophysis. 
Several  papers  have  been  written  recommending  the  blood  pres- 
sure method,  but  our  experience  has  been  that  the  isolated  uterus 
method  is  the  best  so  far  proposed,  as  differences  of  activity  which 
are  only  just  appreciable  by  the  blood-pressure  method,  under  the 
best  conditions,  are  at  once  obvious  in  the  test  on  the  uterus  without 
any  special  care  in  controlling  the  regularity  of  the  response. 
We  are  of  the  opinion,  however,  that  more  concordant  results 
can  be  obtained  by  employing  the  whole  one  horn  of  the  uterus  of  a 
350  to  425  Gm.  pig  as  suggested  by  Pittenger,i  instead  of  only  a 
segment  of  the  one  horn  of  the  uterus  of  a  250  Gm.  guinea  pig;  also 
by  controlling  the  contractions  of  the  uterus  by  means  of  an  es- 
capement wheel  and  bucket  for  holding  shot  instead  of  the  small 
heart  lever  recommended.  When  the  whole  horn  is  usedj  the  heart 
lever  is  not  heavy  enough  to  allow  sufficient  weight  to  be  added  to 
control  the  contractions  of  the  muscle. 
The  assay  for  Liquor  Hypophysis  requires  more  experience  on 
the  part  of  the  operator  than  any  other  biologic  test  in  the  Pharma- 
copoeia, and,  although  compulsory  for  a  U.  S.  P.  product,  it  is  not 
included  in  the  chapter  on  "Biologic  Assays." 
Under  "Liquor  Hypophysis,"  however,  we  find  that  the  product 
must  be  tested  "as  directed  by  the  United  States  Hygienic  Labora- 
'  Pittenger:  "An  Improved  Apparatus  for  Testing  Drugs  upon  the  Isolated 
Uterus,"    Jaur.  A.  Ph.  A.,  June,  1918. 
