62 
Preparation  of  Thyroid  Extract. 
(  Am.  Jour.  Pharm. 
(    February,  1911. 
Stances  not  only  give  no  beneficial  therapeutic  action  but  are  actually 
harmful. 
The  following  experimental  evidence  is  offered  in  partial  substan- 
tiation of  this  statement.  Four  lots  of  guinea  pigs  were  given 
identical  amounts  of  iodine,  .0001  mgm.  of  iodine  for  each  100 
grammes  body-weight.  The  first  lot  in  the  form  of  purified  thyreo- 
globulin, precipitated  from  the  protein  extract  by  acidifying  with 
acetic  acid  and  heating  to  44°  C.  The  second  lot  in  the  form  of  the 
alcohol-soluble  portion  of  the  filtrate  from  the  pepsin  digestion  of 
the  glands.  The  third  lot  in  the  form  of  the  alcohol-soluble  portion 
of  the  residue  from  the  pepsin  digestion  of  the  gland.  The  fourth 
lot  from  the  alcohol-soluble  portion  from  extracts  from  normal 
glands  after  removing  all  the  coagulable  proteid.  The  second  and 
fourth  fractions  give  all  the  proteid  color  reaction,  but  compared 
with  the  nitrogen  content  they  contain  relatively  much  less  iodine. 
The  third  fraction  corresponds  to  iodothyrin,  and  as  will  be  seen 
it  is  very  rich  in  iodine.  To  be  certain  of  the  dose  which  each  ani- 
mal received,  the  administration  was  by  hypodermatic  injection  in 
each  instance.  The  relation  of  iodine  to  nitrogen  in  each  of  these 
substances  was  as  follows  : 
1.  Sheep  thyreoglobulin. 
I  c.c.  solution  contains  1.25  mgm.  nitrogen. 
I  c.c.  contains  0.012  mgm.  iodine. 
I  gramme  nitrogen  contains  .0096  gramme  iodine. 
2.  Pepsin  digestion  filtrate,  alcohol-soluble  portion. 
I  c.c.  contains  7  mgm.  nitrogen. 
I  c.c.  contains  .0375  mgm.  iodine. 
I  gramme  nitrogen  contains  .00535  gramme  iodine. 
3.  Pepsin  digestion  residue,  alcohol-soluble  portion. 
I  c.c.  contains  0.14  mgm.  nitrogen. 
I  c.c.  contains  .09  mgm.  nitrogen. 
I  gramme  nitrogen  contains  .6428  iodine. 
4.  Alcohol-soluble  portion  of  extracts  from  sheep  glands 
after  removing  all  coagulable  proteid. 
I  c.c.  contains  10.22  mgm.  nitrogen. 
I  c.c.  contains  .044  mgm.  iodine. 
I  gramme  nitrogen  contains  .0043  gramme  iodine. 
The  pigs  receiving  iodine  in  the  form  of  the  thyreoglobulin 
increased  fifty  per  cent,  in  weight  during  the  experimental  period, 
which  lasted  nearly  two  months,  and  had  no  pathological  disturbance 
