Tavel,  Krumbein,  and  Paltauf,  on  the  other  hand,  prepared  polyva-
lent sera  from  different  human  strains  without  animal  passage,
and  Menzer  and  Moser  monovalent  strains  which  had  likewise  not
been  passed  through  animals;  while  Aronson  attempted  a  combined
procedure  making  use  of  passed  and  unpassed  organisms  conjointly,
both  in  the  form  of  monovalent  and  polyvalent  preparations.  At
the  present  time  practically  all  these  products  are  in  use,  and  while
they  are  unquestionably  efficacious  in  the  animal  experiment,  the
clinical  evidence  is  still  rather  against  than  in  favor  of  their  real
value.  This  suggests  the  possibility,  of  course,  that  clinicians  may
not  apply  the  sera  as  promptly  in  streptococcus  infections  as  is
done  in  diphtheria,  and  as  a  matter  of  fact  there  is  a  good  deal  of
truth  in  this  criticism.  That  this  factor  may  actually  be  one  of
moment  is  suggested  by  the  fact  that  the  best  results  have  thus  far
been  obtained  in  scarlatina,  where  the  diagnosis  is  reached  at  an


248  PASSIVE  IMMUNIZATION

early  date,  and  where  the  serum  can  be  conveniently  and  system-
atically tested.  In  the  other  streptococcus  infections  the  bacterio-
logical diagnosis  is  frequently  not  made  at  all,  or  it  is  delayed  until
it  would  seem  unreasonable  to  expect  any  favorable  result.  Here,
as  elsewhere,  in  serum  therapy,  the  clinician  should  bear  in  mind
that  the  greatest  good  will  only  be  accomplished,  if  the  various  anti-
sera  are  used  early,  in  sufficient  quantity,  and  usually  in  repeated
doses.
