298  Chemistry  of  Pressor  Compounds.     { Am jlf1y"ri9Harm* 
tracts  with  those  of  epinephrin  suggested  the  identity,  or  at  least  a 
close  chemical  relationship  of  the  pressor  principle  of  the  pituitary 
with  that  of  the  adrenal  glands,  hut  Allers  and  Houssay  31  proved 
that  the  chemical  reactions  of  pituitary  pressor  extracts  were  dif- 
ferent from  those  of  epinephrin,  and  the  method  used  for  isolating 
epinephrin  from  the  suprarenal  glands  failed  to  yield  this  compound 
when  tried  on  pituitary  extracts.  Meyers  32  has  shown  that,  while 
repeated  intravenous  injections  of  epinephrin  produced  arterial 
degeneration  in  rabbits,  pituitrin  caused  almost  no  vascular  changes ; 
and  Cramer 33  has  claimed  that,  while  epinephrin  when  mixed 
with  formaldehyde  rapidly  lost  its  pressor  activity,  Pituitrin  when 
so  treated  retained  this  activity.  Again,  Meltzer  34  claims  there  is  a 
difference  in  action  on  the  enucleated  eye  between  epinephrin  and 
the  commercial  preparation  of  pituitary  glands.  Allers  noted  that 
Pituitrin,  which  is  a  dilute  acetic  extract  of  the  glands,  gave,  like 
epinephrin,  when  treated  with  an  alkali,  an  odor  of  an  alkylamin. 
Fiihner 35  has  recently  stated  that  B-iminazolylethylamine  hydro- 
chloride, or  Histamin,  when  injected  intravenously  into  rabbits,  pro- 
duces the  same  effects  on  blood-pressure  and  the  respiration  as 
Pituitrin,  but  admits  it  is  not  the  active  principle  of  the  pituitary 
gland,  as  this  substance  is  more  toxic  than  a  corresponding  amount 
of  Pituitrin,  and  while  repeated  injections  of  B-iminazolylethyla- 
mine will  give  some  tolerance  to  the  injections  of  the  same,  yet  will 
not  give  immunity  to  Pituitrin,  so  that  at  one  time  Fiihner  suggested 
that  the  active  principle  of  the  pituitary  gland  is  not  B-iminazolyle- 
thylamine, but  related  to  it.    However,  Einis  36  found  that  the.  action 
31  Allers,  R.,  "  Zur  Kenntniss  der  wirksamen  Substanz  in  der  Hypo- 
physis," Munch,  med.  Woch.,  vol.  56,  pt.  2,  p.  1474  (1909)  ;  Houssay,  B.  A. 
"'  Estudios  sobre  la  accion  de  los  cxtractos  hipofisiarios,"  p.  159. 
32  Meyers,  M.  K.,  "  Die  Wirkung  von  intravenosen  Injektionen  von  Hypo- 
physenextrakt,"  Cent.  d.  Allg.  Path.,  vol.  20,  p.  109  (1909)  ;  Etienne  and 
Parrisot,  Arch,  de  med.  Expcr.,  July,  1908,  found  slight  lesions. 
33  Cramer,  W.,  "  On  the  Inactivation  of  Adrenalin  in  vitro  and  in  vivo," 
Proc.  Physiol.  Soc,  p.  xxxvi ;  Jour,  of  Physiol.,  vol.  42  (1911). 
34  Meltzer,  S.  J.,  "  Influence  of  the  Infundibular  Portion  of  the  Hypophy- 
sis upon  the  Pupil,"  Proc.  Soc.  Expcr.  Biol.,  vol.  9,  p.  103  (1912).  See  also 
Kepinow,  p.  261. 
35  Fiihner,  H.,  "  Das  Pituitrin  und  seine  wirksamen  Bestandteile,"  Munch, 
med.  Woch..  vol.  59,  p.  852  (1912)  ;  Kaufmann,  P.,  "Ueber  den  Einfluss  der 
Organextrakte  auf  die  Blutgefasse,"  Zcit.  f.  Physiol,  vol.  27,  p.  532. 
36  Einis,  W.,  "  Ueber  die  Wirkung  des  Pituitrin  und  B-imidazolylethyl- 
amine  auf  die  Herzaktion,"  Biochcm.  Zeits.,  vol.  52,  p.  96. 
