Am/u°iyyi9Po8arm'}     Notes  on  "Physiological  Testing:'  323 
city  in  Professor  Abel's  laboratory.  The  best-known  preparation 
of  the  active  principle  of  these  glands  which  is  on  the  market  is 
that  bearing  the  name  of  Takamine.  Abel  has  shown,  however, 
that  this  preparation  is  not  chemically  pure.  Aldrich,  Abel's  former 
associate,  has  obtained  an  extremely  pure  form  of  this  body,  and 
retained  Takamine's  name ;  but  its  production  by  Aldrich's  method 
is  not  commercially  possible.  This  adrenalin  of  Aldrich  and  Abel's 
later  product,  Epinephrin,  are  probably  identical. 
There  have  been  numerous  attempts  to  assay  these  preparations 
by  color  reactions  produced  by  iodine  and  iron  chloride ;  but,  while 
these  are  fairly  serviceable  with  the  pure  principle,  when  used  with 
preparations  of  the  glands  themselves,  which  are  colored,  they  are 
very  misleading.  It  is  admitted  by  most  investigators  that  the 
physiological  test  is  the  most  convenient  method  of  assaying  them. 
Objections  have,  however,  been  raised  on  account  of  the  extreme 
delicacy  of  the  test. 
The  method  which  has  been  advocated  is  that  by  means  of  the 
frog's  eye  or  that  of  Meyer  by  noting  the  contraction  of  strips  of 
muscle  while  placed  in  the  solution  to  be  tested.  In  this  country 
we  usually  assay  such  preparations  by  determining  the  minimum 
quantity  of  the  solution  which  will  cause  a  rise  in  the  systemic 
blood  pressure  of  a  narcotized  dog  with  the  vagi  nerves  cut,  and 
comparing  this  rise  with  that  produced  by  a  definite  amount  of  the 
pure  active  principle.  The  difficulty  with  all  methods  is  to  decide 
what  preparation  to  use  as  a  standard.  The  ordinary  commercial 
adrenalin  contains  a  certain  amount  of  extraneous  matter  (phos- 
phates), so  that  to  standardize  preparations  accurately  a  high  grade 
of  adrenalin,  such  as  that  of  Aldrich,  or  Abel's  Epinephrin,  should 
be  used. 
A  method  which  offers  a  future  is  the  standardization  against  a 
nitrite  solution,  such  as  recommended  by  Cameron.  He  has  shown 
that  a  definite  amount  of  nitro-glycerine  will  neutralize  the  action 
on  the  blood  pressure  of  a  definite  amount  of  adrenalin.  The  phy- 
siological test  on  blood  pressure  runs  within  about  5  per  cent,  error. 
These  methods  have  been  discussed  in  full  in  my  paper  on  the 
suprarenal  glands. 
The  question  as  to  the  standardization  of  the  thyroids  and 
pituitaries  has  not  yet  been  raised,  but  will  no  doubt  soon  be  opened. 
These  glands  offer  peculiar  difficulties  for  the  biological  assay.  As 
