Am.  Jour.  Pbarm. 
December,  1915. 
•J  Assay  Methods  fo.r  Tincture  of  Aconite. 
539 
From  this  table,  it  is  evident  that  the  four  tinctures  vary  mark- 
edly in  their  ability  to  cause  the  death  of  guinea-pigs.  The  ex- 
tremes of  toxicity  are  represented  by  Tincture  A  and  Tincture  D, 
the  former  being  more  than  seven  times  more  toxic  than  the  latter. 
It  will  be  remembered  that,  by  the  chemical  method  of  assay,  no 
great  variations  could  be  detected. 
There  are  certain  theoretical  objections  to  the  use  of  the  guinea- 
pig  method  in  assaying  aconite  preparations.  It  has  been  shown  by 
Hunt 9  and  others  that  guinea-pigs  are  more  susceptible  to  the  action 
of  certain  poisons  at  one  time  of  the  year  than  at  another ;  in 
other  words,  there  is  a  seasonal  variation  in  their  resistance  to  the 
action  of  these  poisons.  The  importance  of  this  has  been  appreci- 
ated in  regard  to  the  use  of  the  guinea-pig  in  assaying  digitalis 
preparations,  and  we  should  not  lose  sight  of  the  fact  that  a  similar 
variation  according  to  season  may  become  evident  when  aconite 
is  tested  in  this  way.  However,  even  should  the  animals  show  this 
seasonal  variation  in  their  resistance  to  the  toxic  action  of  aconite, 
this  can  have  no  appreciable  influence  on  the  results  secured  when 
all  the  experiments  are  carried  out  during  a  relatively  short  period 
of  time,  as  was  the  case  with  ours. 
It  has  also  been  shown  that  alcohol  interferes  with  the  absorp- 
tion of  digitalis  administered  subcutaneously  to  guinea-pigs,  but 
this  possible  factor  in  the  aconite  assay  has  been  avoided  by  using 
a  constant  dilution.  It  is  conceivable,  however,  that  certain  tinc- 
tures may  contain  relatively  large  amounts  of  extractive  matter 
or  "  colloid  material,"  and  that  this  may  hinder  the  absorption  of 
the  aconitine  when  the  tincture  is  injected  subcutaneously.  In 
order  to  determine  whether  this  was  really  a  factor  of  importance, 
the  four  samples  were  tested  on  cats,  according  to  Hatcher's  method. 
The  following  results  were  secured : 
Table  III. 
Preparation 
Tincture  A 
Tincture  B 
Tincture  C 
Tincture  D 
Lethal  dose  for  cats  in  Cc.  per  gramme  body  weight 
.OOO41 
.OOI72 
.OO230 
.OO388 
It  is  evident,  from  an  examination  of  Tables  II  and  III,  that 
the  physiological' methods  give  roughly  concordant  results.    It  is 
