Am.  Jour.  Pharm. 
December,  1915. 
Method  for  Estimation  of  Pepsin. 
547 
i 
2 
3 
4 
5 
6 
7 
i 
1 
1 
I 
1 
I 
1 
0.6  per  cent.  HQ  Cc.  
i 
1 
1 
1 
1 
1 
0.9 
0.8 
0.7 
0.2 
0.0 
0.0 
Diluted  gastric  juice  
0.1 
0.2 
0.3 
0.8 
1.0 
0.0 
0 
0 
0 
0 
° 
0 
1.0 
3 
3 
3 
3 
3 
3 
3 
Peptic  activity  
125 
62.5 
41 
25 
17 
12.5 
0 
Tubes. 
The  gastric  contents  are  never  filtered,  but  strained  through 
cheesecloth,  as  it  is  believed  in  this  way  less  enzyme  is  absorbed.  The 
dilution  has  been  kept  at  ten  times,  or  greater,  and  water  substituted 
for  boiled  juice  to  make  up  the  final  volume.  This  has  been  done  in 
line  with  Nierenstein  and  Schiff 's  7  procedure,  in  order  to  lessen 
the  amount  of  disturbing  factors,  be  they  proteoses,  peptones,  or 
antiferments.  At  the  same  time  it  serves  in  keeping  the  final  total 
acidity  nearer  0.2  per  cent,  than  if  boiled  unneutralized  juice  were 
added. 
The  pea  globulin  is  made  according  to  Rose's  description  from  the 
ordinary  garden  pea,  Pimm  sativum: 
The  finely  ground  peas,  freed  as  much  as  possible  from  the  outer  coating, 
are  repeatedly  extracted  with  large  quantities  of  10  per  cent,  sodium  chloride 
solution,  the  extracts  combined,  strained. through  fine  bolting  cloth,  and  allowed 
to  stand  overnight  in  large  cylinders  to  deposit  insoluble  matter.  The  super- 
natant fluid  is  siphoned  off  and  saturated  with  ammonium  sulphate.  The  pre- 
cipitate of  albumins  and  globulins  is  filtered  off,  suspended  in  a  little  water, 
and  dialyzed  in  running  water  for  three  days,  until  the  salt  has  been  removed 
and  the  albumins  have  been  dissolved.  The  globulins  are  filtered  off  and 
washed  two  or  three  times  with  water,  to  remove  the  last  trace  of  albumins. 
To  purify  further,  the  precipitate  is  extracted  with  10  per  cent,  sodium 
chloride  solution  and  filtered  until  perfectly  clear.  The  resulting  solution  is 
exactly  neutralized  to  litmus  paper,  by  the  cautious  addition  of  dilute  sodium 
hydroxide,  and  again  dialyzed  in  running  water  for  three  days  to  remove  the 
salts  completely.  The  precipitated  globulins  are  then  filtered  off  and  dried  on 
a  water  bath  at  400  C.  During  the  complete  process  of  separation,  the  proteins 
should  be  preserved  with  a  mixture  of  alcoholic  thymol  and  toluene.  The 
globulins  so  prepared  dissolve,  practically  completely,  in  10  per  cent,  sodium 
chloride  solution,  and  after  slight  acidification  with  hydrochloric  acid  yield  a 
turbid  solution  which  does  not  settle  out  on  standing. 
I  have  found  this  solution  of  globulin  to  settle  out  slightly  in  the 
case  of  controls,  though  as  a  rule  it  remains  in  suspension  and  cer- 
tainly is  much  better  than  the  precipitated  ricin,  which  will  settle 
out  and  rise  to  the  top  of  the  tubes.    If  preserved,  as  Rose  directs, 
