A  jkiuaryPihsa98m'}     Analysis  of  the  Gastric  Contents.  27 
(3)  The  ferments,  pepsin  and  rennin  and  the  rennet  zymogen. 
(4)  The  products  of  the  action  of  rennin  upon  casein.  The  prin- 
cipal proteids  present  are  the  native  proteids  and  the  acid  proteids. 
In  the  later  stage  of  digestion  the  contents  will  contain  the  above 
substances  except  the  organic  salts,  and,  in  addition,  free  hydro- 
chloric acid  and  certain  organic  acids  due  to  the  action  of  the  free 
HC1  upon  the  organic  salts  of  the  food.5 
The  principal  proteid  substances  present  are  albumoses  and  pep- 
tones.6, 7 
In  pathological  conditions  of  the  stomach  we  may  find  absence  or 
diminution  of  one  or  more  of  the  physiological  agents  of  digestion  \ 
and,  in  addition,  the  presence  of  certain  abnormal  substances  not 
produced  in  the  normal  organ.  These  last  substances  are  princi- 
pally certain  organic  acids,  lactic  acid,  butyric  acid,  acetic  acid. 
These  substances  are  present  in  the  normal  contents  only  in  the 
amount  in  which  they  or  their  salts  are  contained  in  the  ingested 
food.  In  pathological  conditions  of  the  stomach  they  may  be  pro- 
duced in  considerable  amounts  as  a  result  of  the  fermentation  of  the 
foods,  principally  the  carbohydrate  foods. 
The  particular  fate  of  the  different  food  elements  in  the  stomach 
is  as  follows  : 
The  native  proteids  are  transformed  in  turn  to  albuminates,  albu- 
moses and  peptones. 
The  albuminoids  are,  to  some  extent,  digested  ;  to  some  extent 
remain  unaltered ;  thus  gelatin  is  transformed  to  gelato-peptone, 
keratin  is  unchanged.8, 9 
The  carbohydrate  food  is  not  digested  by  the  agents  of  gastric 
digestion.  The  hydrochloric  acid  of  the  gastric  juice  has  the 
power  of  inverting  cane  sugar,  but  aside  from  this  the  gastric  secre- 
tions exert  no  influence  upon  the  carbohydrates.10  A  certain 
amount  of  amylolytic  digestion  does,  however,  occur  in  the  stomach 
under  the  influence  of  the  ptyaline  of  the  saliva  brought  into  the 
stomach  with  the  food.    The  digestion  of  cooked  starch  goes  on  in 
3Richet :  Le  Sue  Gastrique,  Paris,  1878.    Gamgee  :  Physiological  Chemistry, 
Vol.  II,  p.  158. 
6  Boas  :  Zeitschr.f.  klin.  Med.,  B.  12,  s.  244. 
7Cahn  :  Zeitschr.f.  klin.  Med.,  B.  12,  s.  34. 
8  Tatarinoff:  Centralbl.  f.  d.  med.  Wassenschaft,  No.  16,  1887. 
9  J.  de  Bary  :  Hoppe-Seyler's  Untersuchung,  H.I,  p.  75. 
10Leube  :  Virchow's  Archiv,  Bd.  88,  s.  222. 
