ADecJembe^907m"}      Opsonic  Theory  and  Tuberculosis.  567 
have  already  heard,  that  normal  serum  contained  a  bacteriotropic 
substance  which  they  termed  opsonin,  and  which  was  specific  for 
the  respective  organisms.  In  1905,  before  the  Royal  Society  of 
London,  Wright  announced  how,  by  means  of  his  technique,  it  was 
possible  to  clear  up  a  questionable  diagnosis  of  tuberculosis,  whether 
as  a  localized  affection  or  general.  His  statement  was  based  on 
much  painstaking  experiment  in  which  he  had  for  a  co-worker  Sur- 
geon Reid.  Not  only  did  he  show  how  this  was  possible  by  exami- 
nation of  the  blood  of  the  suspected  individual,  but  also  by  other 
body  fluids  such  as  pus  from  a  joint  or  the  effusion  from  the  chest  or 
abdominal  cavity.  That  by  studying  the  opsonic  power  of  the  blood 
at  least — because  seemingly  aside  from  the  pioneers  in  this  work 
little  has  been  done  with  the  other  body  fluids — a  fairly  good  inference 
can  usually  be  drawn  as  to  the  existence  or  non-existence  of  tubercu- 
losis, I  think  is  pretty  well  agreed  on  by  most  workers.  A  per- 
sistently low  and  uniform  reading  is  usually  found  in  cases  of  local- 
ized tuberculosis  such  as  gland,  joint  and  skin  infections.  To  the 
contrary,  uniformity  of  curve  is  rarely  observed  in  conditions 
marked  with  constitutional  disturbances.  At  one  time  it  is  high, 
perhaps  twice  as  high  as  normal,  and  a  little  later  abnormally  low. 
Wright  explains  and  with  reason  the  difference  in  the  condition  of 
the  blood  in  these  two  contracted  categories  in  this  wise  :  To  quote 
him,  "  The  condition  of  low  opsonic  power  which  is  associated  with 
strictly  localized  tuberculosis  is  almost  certainly  a  condition  which 
has  preceded  and  has  furnished  the  opportunity  for  infection.  The 
fact  that  the  opsonic  index  continues  persistently  low  after  infection 
has  supervened,  while  it  can  invariably  be  raised  by  appropriate 
inoculations,  indicates  that  the  machinery  of  immunization  with 
which  the  organism  is  furnished,  is  not,  under  the  condition  which 
obtains  in  strictly  localized  tuberculous  infections,  spontaneously 
called  into  play."  The  fluctuations  in  cases  of  active  pulmonary 
tuberculosis  he  lays  to  the  "  periodic  conveyance  of  tuberculous 
elements  into  the  blood  " — an  auto-immunization.  Here,  then,  with 
these  facts  borne  out  one  can  perceive  what  a  valuable  asset  we 
have  in  Wright's  discovery.  Ross  working  with  Wright  pointed 
out  what  is  considered  a  most  trustworthy  test  for  diagnostic  pur- 
poses. His  results  are  extremely  interesting  and  seemingly  very 
conclusive.  In  the  course  of  his  investigations  he  found  that  nor- 
mal serum  when  heated  to  6o°  C.  for  ten  minutes,  no  longer  had  the 
