438 
Diastatic  Action  of  Saliva. 
( Am.  Jour.  Pharm . 
1       Sept.,  1886. 
DIASTATIC  ACTION  OF  SALIVA. 
By  R.  H.  Chittenden  and  H.  E.  Smith. 
For  the  purpose  of  testing  the  diastatic  action  of  saliva  quantita- 
tively, a  1  or  2  per  cent,  solution  of  starch  was  exposed  to  the  action 
of  saliva  at  40°  C.  for  half  an  hour,  and  the  reducing  substances 
formed  were  in  all  cases  calculated  as  dextrose  by  Allihn's  (Zeit.  anal. 
Chem.  xxii,  248)  method.  The  action  of  a  ferment  is  not  proportional 
to  its  amount  until  its  solution  is  much  diluted ;  when  the  dilution  of 
the  saliva  is  as  1 :  50  or  100,  the  diastatic  action  can  be  taken  as  a 
measure  of  the  amounts  of  ferment  present.  The  normal  alkalinity 
of  15  samples  of  saliva  reckoned  in  terms  of  sodium  carbonate  was 
0*097  per  cent.  When  this  is  neutralized  with  0*2  per  cent,  hydro- 
chloric acid,  its  diastatic  action  is  much  increased,  especially  when  the 
dilution  is  1  :  50  or  100 ;  but  the  difference  is  still  pronounced  when 
the  dilution  reaches  1  :  2000.  There  appears,  however,  to  be  no  pro- 
portional relation  between  natural  variations  of  alkalinity  and  diasta- 
tic action,  although  the  addition  of  sodium  carbonate  to  neutral  saliva 
retards  and  finally  stops  the  action  of  ptyalin  in  proportion  to  the 
amount  added  ;  this  occurring  especially  readily  in  more  dilute  solu- 
tions. This  is  not  due  to  simple  dilution,  but  to  the  thereby  di- 
minished percentage  of  proteid  matter,  which  in  the  less  diluted  sa- 
liva possibly  ombines  with  the  carbonate;  and  such  proteid  com- 
pounds have  no  effect  on  the  ferment.  Neutral  peptone,  on  the  con- 
trary, has  a  distinctly  stimulating  effect  on  the  activity  of  neutral 
saliva ;  and  when  proportionate  amounts  of  peptone  and  sodium  car- 
bonate are  added,  the  destructive  action  of  the  latter  is  prevented,  an 
alkaline  proteid  substance  being  probably  formed.  The  influence  of 
free  acid  and  of  acid  proteid  on  the  activity  of  ptyalin  is  important, 
in  view  of  the  rapid  passage  of  the  salivary  secretions  into  the 
stomach.  That  gastric  juice  does  destroy  ptyalin  has  been  shown  by 
Langley  (J.  Physiol.,  iii) ;  the  present  research  was  directed  to  deter- 
mining quantitatively  the  particulars  of  such  action;  the  tropaeolin 
test  being  used  for  the  detection  of  free  acid.  As  a  mean  of  eight  de- 
terminations, 20  c.c.  of  neutralized  saliva  were  found  to  contain  pro- 
teids  capable  of  combining  with  7*74  c.c.  of  0'1  per  cent,  hydrochloric 
acid,  a  result  showing  on  comparison  with  similar  experiments  with 
peptones,  either  that  the  combining  power  for  acid  of  saliva  proteid 
and  peptone  is  different,  or  that  much  acid  is  used  up  in  reacting  with 
