244  Chemistry  of  Digestion.  {Am'M^'iSarxn" 
whenever  the  combined  HC1  is  not  exclusively  in  the  form  of  hydro- 
chlorates  of  amido  acids  (chloride  of  ammonium  hydrochlorates  of 
organic  acids  destructible  by  heat).  In  man,  in  the  physiological 
state,  the  proportion  a  is  pretty  constant. 
To  sum  up,  the  stomach  is,  during  digestion,  the  seat  of  chemical 
phenomena,  evolving  themselves  in  a  regular  manner.  The  rapidity 
of  this  evolution  is  so  much  the  greater  the  simpler  the  food  and 
the  more  it  accords  with  the  digestive  capabilities  of  the  particular 
animal.  It  shows  itself  by  the  variations  in  the  chlorinated  ele- 
ments, among  which  free  HC1  (H)  is,  from  the  quantitative  point  of 
view,  much  the  most  feeble;  whilst,  on  the  contrary,  the  combined 
organic  chlorine  (C)  presents  itself  as  the  most  important  figure  to 
consider  in  the  appreciation  of  the  useful  work  furnished  by  the 
stomach  for  a  definite  mixed  meal. 
When  we  make  several  analyses  of  the  gastric  juice  in  the  same 
animal  under  different  conditions  we  find  the  results  very  constant. 
This  constancy  of  the  factors  indicates  that  they  are  all  the  factors 
active  in  intra-gastric  digestion.  F  (fixed  chlorine)  ought  to  be 
regarded  as  a  secretion,  or  at  the  least  as  the  direct  product  of  the 
elements  secreted  under  the  influence  of  the  simple  excitation  pro- 
duced by  distilled  water.  But  F  and  its  factors  do  not  suffice  to 
peptonize  albuminoid  elements,  and  multiple  agents  intervene  in  the 
digestive  act.  At  the  beginning  of  the  physiological  digestion  of  a 
mixed  meal,  F  does  not  tend  to  rise  above  a  certain  scarcely  vari- 
able limit,  therefore  Na  and  CI  are  utilized  in  another  form  for  the 
elaboration  of  the  foods  during  this  period.  But  in  the  patholo- 
gical state  F  may  increase  or  decrease  much;  we  may  consider  that 
due  to,  either  an  insufficient  use  of  the  chlorine  elements  secreted, 
or  an  insufficient  secretion.  That  is  to  say,  in  the  pathological 
state  the  fixed  chlorine  is  not  used  in  the  normal  manner,  and  that 
may  be  attributed  to  increase  or  diminution  of  other  agents.  What- 
ever the  form  in  which  the  fixed  chlorides  are  utilized  their  chlorine 
is  always  comprised  in  the  total  chlorine  T ;  the  chlorine  may  there- 
fore serve  to  measure  the  chlorhydric  secretion,  and  T  is  an  import- 
ant value  ;  all  things  being  equal  it  varies  but  little  in  the  physiolo- 
gical state,  but  may  vary  with  the  kind  of  test  meal  employed. 
The  utilization  of  the  fixed  chlorides  makes  itself  evident  during 
digestion  by  the  increase  of  the  HC1  combined  or  free;  H  +  C  (that 
is,  the  free  hydrochloric  acid  and  the  organically  combined  HQ)  is 
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