776 
Diphtheria  Antitoxin. 
Am.  Jour.  Pharm, 
Nov.,  1918. 
Immune  serum  is  influenced  by  salts  according  to  physico-chem- 
ical laws  of  salt  albumin  combinations.94  Ammonium  sulphate  in 
50  per  cent,  saturation,  precipitates  globulins  and  antitoxin95  from 
serum,  leaving  the  albumin  in  solution,  but  precipitation  of  the  al- 
bumin occurs  when  the  ammonium  sulphate  saturation  has  reached 
64  per  cent.  By  this  means  it  can  be  shown  that  the  antitoxin  is 
not  an  albumin  or  necessarily  associated  with  them.96  The  fact  that 
in  the  precipitation  by  ammonium  sulphate  there  is  no  accumulation 
of  antitoxin  in  any  one  fraction,  would  argue  against  a  mechanical 
precipitation. 
The  response  to  (NH4)2S04  is  different  if  the  serum  is  first 
diluted  with  weak  (NH4)2S04  and  its  (NH4)2S04  concentration 
then  raised  to  one-half  saturation,  than  when  (NH4)2S04  is  added 
directly  to  undiluted  serum.97  Highly  concentrated  sera  have  dif- 
ferent precipitation  quality  than  dilute.98 
The  globulins  are  usually  divided  into  euglobulins  and  pseudo- 
globulins.  By  precipitation  with  (NH4)2S04,  Freund  and  Joachim 
claim  to  have  separated  the  true  globulins  into  four  fractions.  By 
one  third  saturation,  two  fractions  were  obtained — one  soluble  in 
water,  which  was  called  "  euglobulin  "  and  one  insoluble  in  water 
called  "  paraeuglobulin."  By  half-saturation  two  other  fractions 
were  obtained.  The  one  soluble  in  water  was  named  "pseudo 
globulin  "  and  the  one  insoluble  was  called  "  para-pseudoglobulin."99 
The  ammonium  sulphate  separation  of  euglobulin  from  pseudoglobu- 
lin  is  an  artificial  one,100  and  it  is  still  uncertain  whether  euglobulin 
and  pseudoglobulin  are  distinct  proteins.  The  amino-acid  content 
of  the  two  fractions  is  approximately  the  same.  Dale  and  Hartley 
find  "that  a  rigidly  specific  sensitiveness  to  euglobulin  occurs  com- 
paratively frequently  "  but  they  never  succeeded  by  injection  of 
pseudoglobulin   in   producing   a   sensitiveness   to  pseudoglobulin 
94  Pick,  E.  P.,  and  Schwarz,  O.,  Biochem.  Zeits.,  Vol.  17,  p.  491,  1909; 
Pribram,  E.,  Wien.  klin.  Woch.,  1908,  p.  1079,  Vol.  21.  Look  up  Oryng,  T., 
and  Pauli,  W.,  Biochem.  Zeits.,  191 5,  Vol.  70,  p.  368. 
95  Freund  and  Sternberg. 
96  Banzhaf,  E.  J.,  and  Famulener,  L.  W.,  "  Collected  Studies,"  Bureau  of 
Laboratories,  N.  Y.,  Vol.  8,  1914-15,  p.  208. 
97  Popplewell-Bloxham,  W.,  Proc.  Physiol.  Soc.  Journ.  Physiol.,  Vol.  26, 
p.  xxxiii,  1901. 
98  Brunner,  J.,  and  Pinkus,  S.  N.,  Biochem.  Zeits.,  Vol.  5,  p.  381. 
99  Freund,  E.,  and  Joachim,  J.,  Zeits.  physiol.  Chem.,  Vol.  36,  p.  406,  1912. 
100  Banzhaf  and  Famulener. 
