g6  Analysis  of  the  Gastric  Contents. 
In  this  process  butyric  acid,  potassic  sulpho-cyanide,  fatty  acids 
and  alcohol,  if  present,  are  separated  by  the  addition  of  free  hydro- 
chloric acid  and  subsequent  evaporation.  These  substances  would 
otherwise  be  taken  up  by  the  ether.  The  lactic  acid  is  taken  up  by 
the  ether,  while  the  remaining  substances,  as  glucose,  peptones,  etc., 
remain  in  the  residual  contents.67  This  test  includes  both  free  lactic 
acid  and  lactates.  It  will  not  react  to  the  amount  of  lactic  acid 
contained  in  an  Ewald  test  breakfast.68 
If  it  is  desired  to  detect  the  production  of  very  small  quantities 
of  lactic  acid  (2  grammes  per  mille)  the  method  of  Boas  must  be 
used.  For  this  test  a  meal  containing  no  lactic  acid  is  ingested. 
Boas'  meal  consists  of  an  oatmeal  soup,  prepared  by  boiling  I 
drachm  of  oatmeal  in  1  litre  of  water.  One  or  more  hours  after 
ingestion  the  contents  are  expressed,  and  subjected  to  a  very  deli- 
cate test  for  lactic  acid  devised  by  Boas.67 
According  to  our  present  ideas,  the  production  of  lactic  acid 
during  gastric  digestion  occurs  as  the  result  of  the  fermentation  of 
the  carbohydrate  foods,  through  the  agency  of  certain  bacterial 
organisms.  Whether  the  fermentation  is  due  to  one  definite  organ- 
ism or  to  several  different  forms  of  bacteria  is  not  definitely  settled. 
Huffe  first  demonstrated  by  scientific  methods  a  specific  bacillus  as 
a  cause  of  lactic  acid  fermentation.  This  bacillus  (acidi  lactici)  is  a 
short,  plump,  rod-shaped  organism  I  to  1-7  fi  in  length  by  0-3  to 
0-40  in  thickness.69 
Miller  has  found  several  kinds  of  lactic-acid-forming  bacteria  in 
the  mouth  in  normal  conditions — among  others,  one  similar  to  this 
bacillus  of  Huffe  in  morphological  and  physiological  characteristics.™ 
Kauffman  and  Schlesinger,  Rosenheim  and  others  have  found  that 
the  presence  of  large  numbers  of  a  large  bacillus  of  a  type  found  in 
the  mouth  is  characteristic  of  the  gastric  contents  where  lactic  acid 
is  produced.71'72     The  action  of  this  bacillus  is  inhibited  by  an  acidity 
methods  given  are  that  of  Strauss  {Berl.  klin.  Woch.,  No.  37,  1895),  and  that  of 
Boas  (referred  to  later).  Neither  is  as  simple  as  the  above.  The  ordinarily  used 
Uffieman-Penzolt  test  is  not  free  from  error. 
67  Boas  :  Deutsch.  med.  Woch.,  No.  39,  1893. 
68  De  Jong  :  Archiv.f.  Verdauungskrankheiten,  Bd.  II,  H.  1  ;  also  L,angguth, 
same  Archives,  Bd.  I,  s.  365. 
69  Huffe  :  Mittheil  a.  d.  Reiehsgesundheitsamts,  Bd.  II,  s.  307. 
70  Miller  :  Die  Mikro-organismen  der  Mundhohle,  Leipzig,  1889. 
71  Kaufman:  Bacteriologie  der  Magengahrungen,  Berl.  klin.  Woch.,  No.  6, 
1895. 
72  Rosenheim  :  Loc.  cit.\  also  Virchow's  Archiv,  Bd.  Ill,  s.  414. 
