Am.  Jour.  Pharm. ) 
February,  1902.  J 
Animal  Digestive  Ferments. 
63 
that  we  have  arrived  in  recent  years  at  definite  methods  for  the  pre- 
cipitation and  separation  of  certain  proteids,  albumen,  albumoses, 
peptones,  etc.,  and  the  nitrogenous  crystallizable,  associated  and 
derived  principles  of  the  food. 
In  the  study  of  the  derivatives  of  starch  digestion  similar  difficul- 
ties are  encountered  in  the  separation  of  certain  of  the  soluble 
carbohydrates,  namely,  the  dextrins,  but  their  color  reactions  are  so 
marked  as  to  afford  reliable  and  well-known  methods  for  distin- 
guishing them.  The  crystalline  nature  of  the  sugars,  the  maltose 
and  dextrose,  has  made  their  chemical  constitution  well  known. 
So  we  have  authoritative  methods  for  the  analysis  of  food  and 
food  preparations.  It  is  within  the  power  of  the  analyst  to 
distinguish  between  a  preparation  that  is  merely  a  stimulant  and 
one  that  is,  in  the  strictest  sense,  a  complete  nutritive;  he  is  in  a 
position  to  judge  the  degree  of  the  change  produced  in  the  foods  by 
digestion,  and  to  form  an  opinion  as  to  the  relative  assimilability  of 
foods.  , 
The  coagulated  albumen  may,  in  its  susceptibility  to  ferment 
action,  be  compared  to  gelatinized  starch ;  the  acid-albumen  or 
syntonin,  to  soluble  starch ;  proproteoses,  to  erythrodextrin ;  deu- 
teroproteose,  to  achroodextrin ;  peptone,  to  maltose,  and  the  more 
resistant  antialbumen  or  dyspeptone,  to  cellulose. 
The  methods  by  which  chemists  distinguish  these  various  soluble 
products  in  their  various  stages  of  solubility  belong  to  the  chemical 
side  of  the  subject ;  their  chief  physiological  significance  is  simply 
that  as  the  digestion  proceeds  the  substances  become  more  soluble, 
more  highly  diffusible.  Furthermore,  chemical  analysis  as  applied 
to  these  organic  substances  necessarily  involves  methods  which, 
perfect  for  the  chemist  to  distinguish  their  reactions  and  behavior, 
in  themselves  bring  into  play  agencies  never  encountered  in  physio- 
logical conditions. 
The  influence  of  various  and  single  food  elements — sugars, 
albumen,  gelatines,  albumoses,  peptones,  etc. — have  long  been  the 
object  of  study  in  the  feeding  of  animals.  These  various  substances 
have  also  been  artificially  introduced  into  the  circulation  and  the 
effects  observed. 
When  we  come  to  trace  the  results  of  scientific  research  and 
experiment  in  the  chemistry  of  digestion  as  taking  practical  form 
in  pharmacy  and  medicine,  we  have  to  go  back  but  a  brief  time, 
