io  Resistance  of  Guinea  Pigs  to  Po«onitt^.jAJj™J  llTI.™' 
cent,  alcohol ;  the  other  comprising  those  containing  from  70  to  80 
per  cent,  alcohol. 
The  comparison  of  the  lethal  doses  for  two  tinctures  made  with 
50  per  cent,  alcohol  and  the  lethal  dose  for  ouabain  during  the  same 
months  is  given  in  Table  III.  N 
Table  III. 
June,  1912. 
Oct.,  1912. 
Dec,  1912. 
Jan.,  1913. 
Aug.,  1913. 
Ouabain  
Tr.  Digitalis  U.  S.  P. 
434900  
Tr.  Digitalis  U.  S.  P. 
457579  
. OOOOOO4 
.004 
. OOOOOO42 
.004 
. OOOOOO45 
.007  + 
.0075 
. OOOOOO4 
.OO65 
.00000025 
.OO42 
.0052 
So  far  as  can  be  judged  by  this  limited  number  of  experiments, 
"  seasonal  "  variations  in  the  resistance  of  guinea  pigs  toward  poison- 
ing by  ouabain  and  by  tinctures  of  digitalis  made  with  50  per  cent, 
alcohol  follow  the  same  general  curve.  In  January,  1913,  the  lethal 
dose  for  Tincture  434900  was  .0065,  while  in  July,  1913,  it  showed  a 
decrease  of  35.4  per  cent.:  the  lethal  dose  of  ouabain  showed  a 
decrease  of  37.5  per  cent,  during  the  same  time.  In  December,  1912, 
the  dose  of  Tincture  457579  was  .0075,  while  in  July,  191 3,  it  was 
30.6  per  cent,  less:  the  dose  of  ouabain  suffered  a  decrease  of  44 
per  cent. 
In  testing  the  preparations  containing  relatively  high  percentages 
of  alcohol,  entirely  different  results  were  obtained.  These  are  so 
surprising  that  it  was  only  after  confirming  them  repeatedly  that  I 
could  feel  that  they  were  not  due  to  some  error  in  testing.  The  tests 
were  carried  out  in  a  manner  exactly  similar  to  those  dealing  with 
the  tinctures  just  discussed  and  the  difference  in  the  behavior  seems 
to  depend  upon  an  essential  difference  in  the  composition  of  prepara- 
tions made  with  50  and  75  per  cent,  alcohol  respectively. 
From  these  results,  it  is  evident  that  no  seasonal  variation  has 
been  observed  in  the  resistance  of  guinea  pigs  to  poisoning  by  fluid 
preparations  of  digitalis  made  by  percolation  of  the  leaf  with  men- 
strua containing  70  to  80  per  cent,  alcohol.  Tinctures  made  with 
75  per  cent,  alcohol  differ  in  several  important  points  from  those 
made  with  50  per  cent,  alcohol,  but  it  seems  almost  incredible  that 
the  resistance  of  guinea  pigs  to  poisoning  by  the  two  should  follow 
