A™anuary,Pi898m  }      Analysis  of  the  Gastric  Contents,  43 
pepsin  is  conducted  as  follows  :  50  milligrammes  of  coagulated  egg 
albumin  are  placed  in  25  c.c.  of  the  filtrate  of  the  contents,  and  the 
mixture  kept  at  a  temperature  of  400  C.  If  pepsin  be  present, 
digestion  of  the  albumin  will  occur.  If  no  free  hydrochloric  acid 
be  present  in  the  contents,  the  same  test  is  applied,  the  contents 
having  first  been  brought  to  the  proper  acidity  by  the  addition  of 
hydrochloric  acid. 
These  determinations  performed  in  this  way  also  enable  us  to 
form  some  rough  quantitative  estimation  of  the  pepsin  present.  In 
the  normal  contents,  50  milligrammes  of  egg  is  entirely  dissolved  in 
25  c.c.  of  contents  within  three  hours.  The  acidity  being  normal 
then,  either  naturally  or  by  addition  of  acid,  a  duration  of  the  dis- 
solution of  the  egg  over  three  hours  indicates  a  diminution  in  pep- 
sin.54 
A  more  definite  quantitative  estimation,  suited  to  practical  work, 
may  be  made  as  follows  :55  A  I  per  cent,  solution  of  albumin  (dry) 
containing  4  per  cent,  free  hydrochloric  acid  is  made  up.  This  is 
divided  into  two  portions  of  10  c.c.  each.  To  one  portion  5  c.c.  of 
water  are  added,  to  the  other  5  c.c.  of  the  filtrate  of  the  gastric  con- 
tents to  be  tested.  Both  mixtures  are  then  placed  at  a  temperature 
of  400  C.  for  one  hour.  The  amount  of  albumin  in  each  solution  is 
then  tested  by  means  of  an  Esbach  albuminometer,  and  from  the 
comparative  results  the  per  cent,  strength  of  the  contents  estimated. 
Thus,  if  the  first  solution  shows  6  per  cent,  albumin  and  the  second 
3  per  cent.,  the  contents  are  said  to  have  a  50  per  cent,  strength 
pepsin.  The  normal  contents  give  from  80  per  cent,  to  90  per  cent, 
by  this  test. 
Rennin,  the  milk-curdling  ferment  of  the  stomach,  is  formed  from 
its  zymogen,  which  exists  in  the  cells  of  the  gastric  mucous  mem- 
brane, by  the  action  of  the  secreted  acid.  A  certain  amount  of 
rennin  can,  however,  be  obtained  by  the  addition  of  water  to  the 
mucous  membrane,  even  where  no  free  HC1  is  present  in  the  stomach. 
Rennin  is  active  in  acid,  neutral  or  even  feebly  alkaline  solutions.56 
The  normal  gastric  contents  contain  both  rennin  and  its  zymo- 
gen.57 
5  4  Hammerschlag  :  Naturforscher-Versammluug,  1894,  und  Archiv  d.  Ver- 
dauungskrankheiten,  Bd.  II,  H.  1. 
65  Jaworski  :  Zeitschr.  klin.  Med.,  Bd.  XI,  s.  275. 
56  Heintz  :  Jour.f.prakt.  Chemie,  Neur.  Folg.,  Vol.  VI,  p.  374. 
57  Hainmarsteti:  Mohr'sjahrsbericht,  Vol.  II,  118,  Vol.  IV,  135,  Vol.  VII,  158. 
