AmMarch,Sm- }  -A rtificial  Gastric  Juice.  1 3  7 
that  is,  extract  of  malt  should  completely  digest  its  own  weight  of 
potato  starch  in  10-15  minutes  at  q8°-ioo°  F. 
It  will  be  remarked  that  I  have  selected  potato  starch  or  arrow- 
root for  this  test,  other  starches  giving  widely  differing  results* 
The  accompanying  table  will  indicate  the  importance  of  using  one 
or  other  of  these  kinds  of  starch,  and,  as  mentioned  above,  prob- 
ably suggests  an  explanation  of  the  widely  differing  results  of  other 
observers. 
The  different  mucilages  were  all  prepared  as  described  above, 
and  quantities  of  mucilage  representing  05,  -i  and  -5  grm.  of  each 
starch  (dried)  introduced  into  the  bottles,  the  bulk  of  each  being 
made  up  to  50  cc.  with  distilled  water,  and  -5  grm.  of  extract  of 
malt  added  to  each. — Phar.  Jour,  and  Trans.,  Dec.  21,  1889,  p  481 
THE  INFLUENCE  OF  ARTIFICIAL  GASTRIC  JUICE  ON 
THE  ACETOUS  AND  LACTIC  ACID  FERMENTATIONS. 
By  F.  O.  Cohn. 
Of  the  views  held  concerning  the  origin  of  the  hydrochloric  acid 
in  the  gastric  juice,  one  of  the  most  generally  accepted  is  that 
lactic  acid  formed  from  carbo-hydrates,  liberates  hydrochloric 
acid,  by  acting  on  sodium  chloride  (Ewald).  At  the  same  time, 
it  is  well  known  that  acidity  stops  fermentative  processes,  and  it 
is  therefore  important  to  determine  accurately  what  influence 
gastric  juice  exerts  on  the  acetic  acid  and  lactic  acid  fermentations, 
and  what  concentration  of  hydrochloric  acid  stops  the  fermentation. 
In  the  present  research  an  artificial  gastric  juice  was  made  with 
the  Pepsinum  germanicum  of  Witte  of  Rostock  ;  the  micro-organisms 
of  the  acetic  and  of  the  lactic  fermentations  were  grown  in  suitable 
saline  media.  This  was  titrated  with  normal  sodium  hydroxide 
solution  before  and  after  infection  with  the  micro-organisms  in 
question.  The  influence  on  the  rate  of  fermentation  of  (1)  pepsin, 
(2)  hydrochloric,  acid,  (3)  pepsin  and  hydrochloric  acid,  and  (4) 
hydrochloric  acid  in  the  presence  of  peptone,  was  investigated ; 
some  experiments  were  also  made  to  determine  the  amount  of 
decomposition  of  phosphates  brought  about  by  hydrochloric  acid. 
The  results  obtained  were  as  follows : 
(1)  Pepsin  does  not  hinder  either  the  acetic  or  the  lactic  acid 
1  Zeit.  physiol.  Chem.,  xiv,  75-105,  Jour.  Chem  Soc,  [889,  p.  1227. 
