Am.  Jour.  Phann. 
May,  1914. 
Autogenous  Vaccines. 
209 
they  contain,  may  result  in  the  extraleucocytic  lysis  of  so  many 
bacteria  that  the  resultant  flooding  of  the  tissues  with  large  quan- 
tities of  their  contained  endotoxin  may  imperil  the  life  of  the 
recipient  from  the  additional  toxaemia." 
Bacteria  have  a  selective  action :  not  only  must  they  gain  access 
to  the  body  in  large  enough  numbers  and  possessing  sufficient 
virulence,  but  they  must  also  gain  entrance  to  a  tissue  that  is  suit- 
able for  their  further  development.  For  instance,  you  can  rub  a 
typhoid  culture  into  an  abraded  surface  of  the  arm  or  a  culture 
of  streptococci  can  be  swallowed,  both  with  equal  impunity,  but 
reversing  the  conditions  a  bacterial  infection  is  sure  to  follow. 
Now  what  are  the  general  defences  of  the  body  against  this 
bacterial  invasion  ?    They  are  fourfold  : 
1.  Antitoxin,  a  substance  manufactured  by  the  tissues  which 
is  capable  of  neutralizing  the  soluble  toxins  produced  by  certain 
groups  of  bacteria. 
2.  Agglutinin,  a  substance  which  causes  bacteria  free  in  the 
tissues  or  blood  stream  to  be  clumped  together  in  masses  and  held 
nearly  immovable  and  therefore  more  accessible  for  phagocytosis. 
This  is  the  more  conspicuous  where  it  concerns  the  motile  bacteria. 
Though  originally  observed  in  1889  by  Charrin  and  Rogers,  in 
studying  the  Bacillus  pyocyaneus,  the  agglutination  reaction  is  com- 
monly associated  with  Widal,  who  first  applied  the  phenomenon  in 
the  diagnosis  of  disease  by  an  unknown  organism. 
3.  Lysin,  a  substance  or  substances  elaborated  by  the  body  which 
has  the  property  of  dissolving  certain  bacteria.  PfeifTer  noted  that 
guinea  pigs  which  had  been  immunized  against  cholera  bacilli  could 
withstand  the  further  intra-peritoneal  injection  of  virulent  cultures 
without  harm,  and  found  that  the  peritoneal  fluids  dissolved  the 
organisms. 
4.  Opsonin,  discovered  and  named  by  Wright,  is  a  substance  that 
prepares  or  sensitizes  the  bacteria  for  ingestion  by  the  phagocytic 
elements  of  the  white  blood-corpuscles. 
There  are  two  types  of  bacterial  infection :  local  and  general. 
The  former  is  best  represented  by  boils ;  the  latter  is  seen  in  diseases 
like  typhoid  fever,  pneumonia,  puerperal  sepsis,  and  the  like.  When 
a  person  recovers  from  a  bacterial  disease  like  typhoid  fever,  it  is 
by  the  body  having  gradually  elaborated  the  foregoing  antitoxins, 
agglutinins,  lysins,  and  opsonins  in  amounts  sufficient  to  cause  the 
neutralization,  destruction,  and  solution  of  the  bacteria.    The  time 
