72 
relatively  slight  in  amount.  The  cause  of  such  variation  is  not  easy 
to  determine.  The  amount  of  squeezing  to  which  the  finger  may  be 
subjected  stands  in  no  definite  relation  to  the  intensity  of  the  bands 
present,  though  mechanical  injury  to  the  red  cells,  as  in  whipping 
blood,  produces  some  degree  of  laking  ;  nor  does  the  length  of  time 
(up  to  one  and  a  half  hours)  during  which  the  oxalated  blood  is 
kept  before  cenfrifugalisation  ordinarily  affect  the  strength  of  the 
bands  in  any  definite  manner.  The  only  circumstance  which 
Table  32.  Examination  of  oxalated  blood  plasma,  for  the  presence  of  dissolved  haemo¬ 
globin,  in  patients  not  suffering  from  blackwater  fever. 
No.  of 
Obser¬ 
vation 
Condition  present  in 
subject  supplying  plasma 
Amount 
of  blood  ; 
amount  of 
potassium 
oxalate 
solution 
Colour  of  oxalated 
plasma  in  a  layer 
3  mm.  thick 
I-ength  of 
column 
examined 
with 
spectroscope 
Percentage  of 
haemoglobin 
in  the  blood 
plasma 
I 
Malaria  (Indian) 
4  :  I 
Light  orange 
18  mm. 
0-3'  % 
2 
T.  101°  F . 
'J 
Light  orange 
„ 
°->3% 
3 
Gumraata  of  livt^r  ... 
Light  orange 
o-'3% 
4 
Herpes  Zoster 
3’ 
Light  orange 
0T0% 
5 
Malaria  . 
3? 
Light  orange 
°->3% 
6 
Malaria 
M 
Light  orange 
0-10% 
7 
„  (six  days  later) 
33 
Light  orange 
0-10% 
8 
,,  (seven  days  later) 
Light  orange 
°’3'  % 
9 
Malaria  (Indian) 
Light  orange 
o-o6% 
TO 
Malaria  ...  . 
Light  orange 
°-'3% 
I  T 
Typhoid 
Light  orange 
o-i6% 
12 
IVIalaria 
33 
Light  orange 
0-02  % 
'3 
Malaria 
33 
Dark  orange 
°'°9  % 
'4 
„  (one  day  later) 
33 
Dark  orange 
0-20  % 
15 
Diarrhoea 
Light  orange 
°'°5  % 
16 
T.  102°  F . 
3* 
Light  orange 
0-04  % 
'7 
Dysentery  . 
33 
Orange 
0'i6% 
18 
Dysentery 
35 
Light  orange 
0-04  % 
Malaria 
53 
Light  orange 
°'’5% 
20 
Malaria 
33 
Orange 
21 
Malaria 
33 
Light  orange 
35 
0-07  % 
constantl}^  affected  the  haemoglobin  bands  was  the  occurrence  of 
clotting.  If  a  clot  formed,  the  serum  expressed  always  showed 
stronger  haemoglobin  bands  than  the  plasma,  and  if  a  sterile  clot  was 
allowed  to  stand  for  three  hours  the  serum  in  contact  with  it  usually 
showed  in  a  thickness  of  5  mm.  to  7  rom.,  a  reddish  tint  just 
recognisable  with  the  naked  eye.  The  haemoglobin  bands,  moreover, 
are  deepest  in  those  portions  of  the  serum,  which  are  last  exuded. 
If  the  clot  is  broken  up  with  a  glass  rod  the  red  coloration  becomes 
deeper. 
