A  j;Saryfih898rm'}     Analysis  of  the  Gastric  Contents.  33 
The  failure  of  any  agent,  or  of  its  normal  amount,  may,  at  the 
same  time,  point  to  the  malady  in  a  given  case,  and  suggest  a  treat, 
ment. 
The  presence  of  the  abnormal  substances  not  produced  in  the 
normal  stomach  is  itself  an  indication  of  a  pathological  process,  and, 
to  some  extent,  of  the  nature  of  this  process. 
Of  secondary  value  may  be  the  determination  of  the  separate 
products  of  the  proteid  and  carbohydrate  digestion  in  the  stomach. 
Some  writers  ascribe  considerable  importance  to  these  tests,  espe- 
cially the  tests  for  starch  and  dextrin  in  the  gastric  contents;  but 
recent  works  and  my  own  observations,  given  later  in  this  paper, 
tend  to  show  that  very  little,  if  any,  useful  information  can  be 
obtained  by  these  tests.32 
In  detail,  the  chemical  analysis  includes  the  following  determina- 
tions : 
The  reaction.  * 
The  presence  of  free  acids. 
The  qualitative  determination  of  free  hydrochloric  acid,  lactic 
acid,  butyric  acid,  acetic  acid,  pepsin,  rennin  and  the  zymogen. 
The  quantitative  determination  of  the  total  acidity,  and  of  the 
total  hydrochloric  acid  and  of  its  factors,  the  total  free  and  total 
combined  HQ. 
The  determination  of  the  digestive  capacity  of  the  contents. 
In  certain  cases  the  following  determinations  may  be  useful,  in 
addition  to  the  above  test : 
The  qualitative  determination  of  starch,  erethodextrin  and  achro- 
dextrin. 
The  qualitative  determination  of  native  proteids,  acid  albumin, 
albumoses  and  peptones. 
The  quantitative  determination  of  the  total  organic  acids. 
The  quantitative  determination  of  the  total  acid  salts. 
The  determinations  of  the  hydrochloric  acid  ot  the  contents 
include : 
(1)  The  detection  of  free  hydrochloric  acid. 
(2)  The  quantitative  estimation  of  the  total  free  hydrochloric 
acid. 
(3)  The  quantitative  estimation  of  the  total  combined  hydrochloric 
acid. 
32  See  Bwald  :  Klinikder  Verdauungskrankheiten,  Vol.- II,  s.  51, 
