AmAug.^'i89oarm'}    Artificial  and  Natural  Digestions.  415, 
saliva;  the  great  contrast  between  natural  and  artificial  digestion  or 
starch  is  the  appearance  of  large  quantities  of  dextrin  in  the  latter 
case  (opinions,  however,  differ  as  to  the  relative  amounts  of  sugar 
and  dextrin  formed),  whilst  in  the  stomach  and  intestines  mere 
traces  of  the  dextrins  are  discoverable.  Nothwithstanding  imper- 
fections in  the  present  method  of  experimentation,  which  are  freely 
admitted,  the  contrast  between  a  digestion  carried  on  in  the  moving 
dialyser  and  in  a  flask  is  very  marked ;  the  iodine  reaction  of  starch 
or  dextrin  disappears  first  in  the  contents  of  the  dialyser ;  in  pro- 
longed digestions  the  contents  of  the  dialyser  remain  clear  and 
more  free  from  putrefactive  organisms  than  those  of  the  flask,  and 
the  proportion  of  dextrin  present  is  less  in  the  dialyser  than  in  the 
flask.    This  last  point  may  be  illustrated  by  the  following  table  : 
Duration 
of  experi- 
ment in 
hours. 
Strength 
of  starch 
in  solution 
per  cent. 
Dextrin 
per  cent, 
in 
dialyser. 
Maltose 
per  cent, 
in 
dialyser. 
Maltose 
per  cent, 
in 
dialysate. 
Dextrin 
per  cent, 
in  flask. 
Maltose 
per  cefit. 
in  flask. 
I 
6 
9*4 
7-67 
15*23 
2 
22 
2*4 
8-58 
14-16 
84-23 
3 
21 
4*23 
1678 
36-62 
61 -8i 
4 
68 
4-23 
8-48 
357o 
62-33 
5 
18 
0-43 
10-31 
12*42 
76-67 
6 
48 
4-18 
I2*6l 
14-20 
71*15 
7 
90 
3*35 
4-29 
3-06 
91-18 
The  conclusions  drawn  from  these  and  similar  experiments  arc 
as  follows : 
When  the  digestion  ot  starch  by  saliva  is  carried  out  under  con- 
ditions which  ensure  a  very  considerable  removal  of  the  products 
(maltose)  as  they  are  formed,  then  : 
(1)  The  rate  at  which  the  digestion  takes  place  is  increased. 
(2)  The  total  amount  of  starch  converted  into  sugar  is  much 
greater,  and  the  residue  of  dextrin  is  much  less,  than  under  condi- 
tions, otherwise  similar,  when  the  products  are  not  removed. 
(3)  The  influence  of  the  removal  of  digestion  products  on  the 
relative  amounts  of  dextrin  and  maltose  formed  is  least  marked 
when  the  starch  solution  is  dilute. 
(4)  These  results  justify  the  assumption  that  in  the  alimentary 
canal  starch  is  completely  converted  into  sugar  before  absorption. 
(5)  The  experiments  afford  no  evidence  that  any  sugar  other  than 
maltose  is  formed  by  the  action  of  saliva  on  starch. 
