Am'juiyr'i^4arm'}    Chemistry  of  Pressor  Compounds.  299 
of  B-iminazolylethylamine  on  the  frog  heart  was  different  from  that 
of  Pituitrin.  It  is  difficult  to  understand  how  this  substance  could 
be  the  active  pressor  constituent  of  the  pituitary  glands,  because  in 
carnivora  it  produces  a  fall  in  blood-pressure,  although  it  produces 
a  rise  in  pressure  in  herbivora,  while  pituitary  extracts  cause  a  rise 
in  rabbits  and  dogs.37 
Kepinow  has  pointed  out  a  synergism  between  the  action  of  epine- 
phrin  and  pituitary  extracts;  that  is,  small  doses  of  epinephrin  are 
claimed  to  increase  the  action  of  pituitary  extracts  so  that  the  com- 
bined action  corresponds  to  more  than  their  simple  addition.  Small 
inactive  doses  of  extracts  of  the  hypophysis  increase  the  action  of 
epinephrin  on  rabbits ;  in  other  words,  the  animal  becomes  sensi- 
tized.38 
Chemical  Experiments. 
Considerable  chemical  work  has  been  done  on  the  pituitary 
glands,  but  apparently  no  pure  pressor  compound  has  as  yet  been 
definitely  isolated.  Calcium,  phosphorus,  bromine,  arsenic,  guanin, 
and  cholin  have  been  found  to  occur  in  the  glands,  and,  while  iodine 
was  suspected,  owing  to  an  apparent  histological  resemblance  be- 
tween the  thyreoid  and  pituitary  glands,  as  yet  it  has  not  been  proved 
to  be  present. 
According  to  our  experiments,  repeated  evaporation  of  extracts 
of  the  pituitary  gland,  and  also  putrefaction,  will  cause  rapid  dimi- 
nution in  pressor  activity.  Schaefer  and  Herring 39  noted  that 
trvptic  digestion  for  18  hours  did  not  destroy  its  diuretic  or  pressor 
action,  and  that  peptic  digestion,  while  it  did  not  injure  its  diuretic 
action,  changed  the  character  of  the  pressor  action. 
Oliver  and  Schaefer  found  that  aqueous  extracts  of  pituitary 
glands  could  be  boiled,  at  least  for  a  short  time,  with  little  or  no  loss 
in  pressor  activity.  Aldrich  40  extracted  the  fresh  infundibular  por- 
tion of  the  gland  with  dilute  acetic  acid  and  then  removed  the  coag- 
37  Dale,  H.  H.,  and  Laidlaw,  P.  P.,  "  Physiological  Action  of  B-iminaz- 
olylethylamine," Jour.  Physiol.,  vol.  41,  p.  318  (1910-11). 
38  Kepinow,  "  Ueber  den  Synergismus  von  Hypophysis  Extrakt  und  Adre- 
nalin," Arch.  f.  expcr.  Path.,  vol.  67,  p.  247  (1912). 
:!n  Schaefer  and  Herring,  /.  c,  p.  22. 
40  Aldrich,  T.  B.,  "  Preliminary  Contribution  to  the  Chemistry  of  the 
Infundibular  Portion  of  the  Pituitary  Body,"  Amer.  Jour.  Phys.  (1907-08), 
vol.  21,  p.  xxiii. 
