28  Analysis  of  the  Gastric  Contents.     { ^J^ffiS™- 
the  stomach  through  the  influence  of  this  ptyaline  until  inhibited 
by  the  increasing  acidity  of  the  contents.11-  12 
The  fats  are  not  digested  in  the  stomach.  The  proteid  envelopes 
of  the  fat  cells  are  digested  away,  allowing  the  fat  globules  to  run 
together,  and  thus  preparing  the  fat  for  the  action  of  the  intestinal 
digestion.13 
The  duration  of  digestion  in  the  stomach,  the  rapidity  of  the 
appearance  of  free  hydrochloric  acid  in  the  contents,  and  the  quan- 
tity of  the  secretion  of  the  physiological  agents  necessary  for  com- 
plete digestion  are  directly  dependent  upon  the  quantity  and  quality 
of  the  food.14 
Thus  ioo  grammes  of  raw  beef  plus  300  c.c.  of  water  are  digested 
in  tivo  hours.15  The  same  amount  of  beef  roasted  takes  three  hours. 
The  duration  of  the  digestion  of  an  Ewald  test  breakfast  (one  roll, 
weight  35  grammes,  and  300  c.c.  of  water)  is  from  two  to  two  and 
one-half  hours.  The  digestion  of  a  Leube  meal  (soup,  meat  and 
bread)  is  from  six  to  seven  hours.16 
Free  hydrochloric  acid  appears  in  the  normal  stomach  from  fif- 
teen to  twenty  minutes  after  the  ingestion  of  35  grammes  of  bread 
with  water ;  twenty-five  to  thirty-five  minutes  after  the  ingestion  of 
twice  this  amount  (70  grammes) ;  twenty-five  to  thirty-five  minutes 
after  60  grammes  of  meat ;  sixty  to  ninety  minutes  after  egg  albu- 
min ;  forty-five  minutes  after  a  mixed  meal  of  bread,  meat  and  vege- 
tables. The  addition  of  fat  to  a  meal  delays  the  appearance  of  ree 
HC1.  The  replacing  of  a  certain  amount  of  meat  by  a  potato 
delays  the  appearance  of  the  HC1. 
The  total  amount  of  the  free  hydrochloric  acid  may  rise  after  a 
light  meal  (Ewald  meal)  to  2-2  grammes  per  mille,  after  a  full 
meal  (Leube)  to  3-3  grammes  per  mille.17    This  maximum  mark  is 
1 1  Ptyaline  digests  cooked  starch  to  dextrin  and  maltose  at  the  body  tem- 
perature in  neutral,  alkaline  or  faintly  acid  solutions.  Chittenden  :  American 
Chemical  Journal,  Vol.  Ill ;  Studies  from  Yale  Laboratory  of  Physiological 
Chemistry,  1884-85. 
12  The  action  of  ptyaline  is  inhibited  in  an  acidity  of  '14  per  cent,  free  HC1, 
•27  per  cent,  combined  HC1.    Langley:  Journal  of  Physiology,  Vol.  III. 
13  Cash,  Archiv  f.  Anat.  and  Physiol.,  1880,  claims  that  small  quantities  of 
the  fats  are  broken  up  by  the  action  of  the  HC1  to  fatty  acids. 
14  Ewald  and  Boas  :  Virchow's  Archiv,  Vol.  CI,  s.  3  5. 
15  Lassen:  Zeitschrift f.  Biologie,  Vol.  XIX. 
1 6  Leube  :  Deutsches  Archiv,  Bd.  XXXIII.  . 
1  7  Kwald  :  Klinik  der  Verdauungskraukheiten,  Vol.  II. 
