﻿142 
  

  

  Dr. 
  H. 
  H. 
  Dale. 
  

  

  the 
  animal 
  is 
  said 
  to 
  be 
  anaphylactic, 
  and 
  the 
  sudden 
  reintroduction 
  of 
  the 
  

   foreign 
  protein 
  may 
  lead 
  to 
  the 
  death 
  of 
  the 
  individual 
  in 
  defence 
  of 
  the 
  

   type. 
  A 
  discussion 
  of 
  the 
  teleology 
  of 
  the 
  condition 
  would 
  lead 
  us 
  too 
  far 
  

   into 
  considerations 
  of 
  the 
  pathology 
  of 
  infection. 
  I 
  may 
  content 
  myself 
  with 
  

   pointing 
  out 
  that 
  the 
  sudden 
  introduction 
  of 
  a 
  foreign 
  protein 
  into 
  the 
  general 
  

   circulation 
  is 
  not 
  a 
  natural 
  event. 
  An 
  animal 
  may 
  be 
  highly 
  immune 
  to 
  

   infection 
  with 
  a 
  micro-organism 
  through 
  natural 
  channels, 
  and 
  yet 
  anaphy- 
  

   lactic 
  to 
  the 
  proteins 
  of 
  that 
  organism 
  introduced 
  by 
  artificial 
  means. 
  A 
  

   generalised 
  anaphylactic 
  reaction, 
  the 
  anaphylactic 
  shock, 
  is 
  a 
  creation 
  of 
  the 
  

   injection 
  needle. 
  A 
  localised 
  anaphylactic 
  reaction, 
  on 
  the 
  other 
  hand, 
  

   defends 
  the 
  system 
  from 
  invasion 
  at 
  the 
  expense 
  of 
  the 
  tissues 
  immediately 
  

   affected. 
  Anaphylaxis, 
  as 
  we 
  see 
  it 
  in 
  the 
  laboratory, 
  is 
  not 
  the 
  opposite 
  of 
  

   immunity 
  ; 
  it 
  is 
  the 
  physiological 
  response, 
  of 
  an 
  animal 
  in 
  a 
  certain 
  phase 
  of 
  

   immunity, 
  to 
  the 
  artificial 
  test 
  which 
  we 
  impose. 
  

  

  The 
  most 
  interesting 
  feature 
  of 
  this 
  defensive 
  mechanism 
  is 
  the 
  exquisite 
  

   fineness 
  of 
  its 
  discrimination 
  between 
  foreign 
  proteins, 
  which 
  by 
  ordinary 
  

   physical 
  and 
  chemical 
  methods 
  are 
  indistinguishable. 
  All 
  attempts 
  to 
  

   explain 
  the 
  reactions 
  of 
  immunity 
  on 
  electro-chemical 
  lines, 
  to 
  compare 
  the 
  

   precipitin 
  -reaction, 
  for 
  example, 
  to 
  the 
  mutual 
  precipitation 
  of 
  two 
  oppositely 
  

   charged 
  amphoteric 
  colloids, 
  are 
  at 
  least 
  premature, 
  in 
  that 
  they 
  fail, 
  in 
  the 
  

   present 
  state 
  of 
  knowledge, 
  to 
  account 
  for 
  this 
  phenomenon 
  of 
  specificity. 
  

   "Whatever 
  the 
  difference 
  may 
  be 
  between 
  the 
  proteins 
  which 
  the 
  reaction 
  

   differentiates, 
  it 
  is 
  nothing 
  so 
  obvious 
  as 
  a 
  difference 
  in 
  the 
  isoelectric 
  point. 
  

   On 
  the 
  other 
  hand, 
  a 
  mere 
  analysis 
  into 
  amino-acids 
  often 
  shows 
  no 
  

   difference 
  in 
  composition. 
  Osborne 
  and 
  Wells 
  found 
  that 
  corresponding 
  

   proteins, 
  from 
  seeds 
  of 
  plants 
  belonging 
  to 
  the 
  same 
  order, 
  e.g., 
  the 
  gliadins 
  

   from 
  wheat 
  and 
  barley, 
  contained 
  the 
  same 
  amino-acids 
  in 
  apparently 
  the 
  

   same 
  proportions, 
  though 
  the 
  anaphylactic 
  reaction 
  detected 
  a 
  difference 
  

   between 
  them. 
  It 
  is 
  obvious, 
  however, 
  that 
  a 
  mere 
  analysis 
  into 
  amino- 
  

   acids 
  tells 
  very 
  little 
  concerning 
  the 
  structure 
  of 
  the 
  molecule. 
  The 
  vast 
  

   number 
  of 
  different 
  ways 
  in 
  which 
  an 
  identical 
  large 
  assortment 
  of 
  amino- 
  

   acids 
  can 
  be 
  linked 
  together 
  offers 
  almost 
  indefinite 
  possibilities 
  of 
  variation 
  

   in 
  the 
  intimate 
  pattern 
  of 
  the 
  molecular 
  fabric. 
  

  

  The 
  recent 
  work 
  of 
  Dakin 
  and 
  Dudley 
  has 
  given 
  the 
  first 
  hint 
  of 
  a 
  connec- 
  

   tion, 
  between 
  variation 
  in 
  molecular 
  configuration 
  and 
  the 
  specific 
  difference 
  

   of 
  corresponding 
  proteins. 
  When 
  a 
  protein 
  is 
  racemised 
  as 
  far 
  as 
  possible 
  

   by 
  warmiag 
  with 
  alkali, 
  and 
  then 
  subjected 
  to 
  complete 
  hydrolysis, 
  some 
  

   of 
  the 
  amino-acids 
  are 
  found 
  to 
  have 
  undergone 
  complete 
  racemisation, 
  

   while 
  others 
  retain, 
  to 
  a 
  greater 
  or 
  less 
  degree, 
  their 
  original 
  optical 
  

   activity. 
  Dakin 
  has 
  given 
  reason 
  for 
  believing 
  that 
  the 
  amino-acids 
  which 
  

  

  