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ME.  J.  LISTEE  ON  THE  EAELT  STAGES  OF  ENFLA^^JAIATION. 
The  red  corpuscles  also  often  adhere  to  the  colourless  ones. 
It  will  be  seen  hereafter  that  the  corpuscles  of  blood  within  the  vessels  of  the  li^ang 
body  present  great  varieties  of  adhesiveness,  according  to  the  amount  of  iiaitation  to 
which  a part  may  be  subjected;  such  variations  are  also  met  with  in  blood  outside  the 
body,  in  consequence  of  differences  in  the  quality  of  the  plasma. 
If  a drop  of  very  thick  solution  of  gum-arabic,  freshly  prepared  and  free  from  acidity, 
be  added  to  about  four  drops  of  blood,  the  red  corpuscles  of  the  mixture  will  be  found 
to  aggregate  much  more  speedily  and  more  closely  than  those  of  ordinaiy  blood,  a fact 
ascertained  some  years  ago  by  Mr.  Whaetox  Joxes  and  some  other  obseiwers*.  The 
result  is  the  formation  of  dense  orange  masses  mth  large  colourless  interspaces,  but 
without  much  regular  appearance  of  rouleaux.  On  closely  examining  such  a specimen, 
the  red  discs  are  seen  to  be  much  diminished  in  breadth  and  increased  in  thickness,  and 
exhibit  an  extreme  degree  of  adhesiveness,  sticking  together  indifferently  by  theii’  edges, 
or  any  other  parts  that  happen  to  come  first ; and  if  one  of  the  masses  be  stretched  so 
as  to  break,  the  separating  corpuscles  become  drawn  out  into  long  viscid  processes, 
which  at  length  give  way  in  the  middle,  and  each  half  is  di-awn  into  its  respective 
corpuscle. 
This  remarkable  effect  cannot  be  accounted  for  by  the  mere  ^iscidity  of  the  plasma, 
which  would  not  make  the  corpuscles  adhere  to  each  other  more  intimately  than  usual, 
unless  they  had  themselves  experienced  some  change,  of  which,  indeed,  their-  altered 
form  is  conclusive  evidence.  Further,  if  a very  small  quantity  of  acetic  acid  be  added 
to  the  gum  before  mixing  it  with  the  blood,  the  corpuscles  null  be  found  to  have  lost 
altogether  their  adhesive  character,  although  the  mixture  may  be  made  -viscid  to  any 
degree  that  may  be  desfied.  A little  acid  perspiration  on  the  finger  appears  to  prevent 
entu’ely  the  formation  of  rouleaux  in  a drop  of  blood  taken  from  it ; but  after  the  finger 
has  been  washed,  the  usual  appearances  present  themselves  when  more  blood  is  di-awn. 
Diminished  adhesiveness  of  the  red  corpuscles  is  also  the  earliest  evidence  of  the  che- 
mical action  of  tincture  of  cantharides  and  croton  oil  on  the  blood  of  the  frog.  A similar 
effect  is  produced  when  a drop  of  human  blood  is  shed  into  a little  fresh  almond  or  ohve 
oil  on  a plate  of  glass,  and  stirred  slightly  so  as  to  break  up  the  blood  into  mmute  drops. 
On  microscopic  examination  of  such  a mixture,  one  sees  the  red  discs  aggregated  as 
usual  in  the  interior  of  the  larger  drops ; but  at  their  exterior,  which  is  in  contact  with 
the  oil,  and  throughout  the  smaller  di-oips,  the  corpuscles  are  somewhat  altered  in  form, 
being  of  less  diameter,  but  thicker,  though  still  in  the  form  of  discs,  and  at  the  same 
time  they  are  found  to  have  lost  every  trace  of  a tendency  to  adhere  together;  and  when 
present  in  a thin  layer  of  blood  they  stand  apart  at  equal  distances  from  one  anotlier. 
as  if  exercising  a mutual  repulsion,  at  the  same  time  exliibiting  molecular  movements 
If  a drop  of  blood  freshly  shed  upon  a glass  plate  be  stfr-red  uith  a needle  in  an  atmo- 
sphere of  chloroform  vapour,  the  rouleaux  will  be  found  to  form  less  perfectly  in  pro- 
portion to  the  time  that  the  chloroform  has  acted,  until,  if  the  period  be  as  long  as 
* Guy’s  Hospital  Eeports,  vol.  viii.  p.  73. 
