Am.  Jour.  Pharm.  > 
Dec,  1883.  J 
Diastatic  Ferment  of  Bacteria. 
625 
With  regard  to  this  unequal  power  of  resistance  shown  by  different 
kinds  of  starch,  the  author  concludes  from  his  further  observations, 
that  the  difference  of  rapidity  with  which  a  given  kind  is  attacked 
and  dissolved  by  a  ferment  is  inversely  proportional  to  its  density, 
provided  always  that  the  granules  in  question  are  entire  and  uninjured 
by  cracks  or  fissures.  In  the  same  way  are  explained  the  differences 
in  point  of  time  in  which  granules  of  the  same  kind  are  sometimes 
observed  to  undergo  change  accordingly  as  these  are  intact  or  otherwise. 
The  cause  of  potato-starch  or  of  bean-starch,  and,  even  under  certain 
conditions,  wh eaten  starch  resisting  attack,  in  spite  of  the  abundant 
presence  of  bacteria,  is  apparently  to  be  sought  for  in  the  fact  that 
other  more  easily  accessible  sources  of  carbon  nourishment  were  also 
present,  certain  albuminoid  constituents  of  the  potato  slices  or  of  the 
beans  employed  affording  this  more  readily  than  the  starch  granules, 
just  as  in  the  experiments,  above  cited,  with  wheaten  starch  solution^ 
and  solid  wheaten  starch ;  the  former  was  preferentially  attacked ;  only 
after  all,  or  at  least  the  chief  portion  of  the  albuminoids  present,  had 
been  used  up  was  the  starch  in  these  cases  attacked. 
Experiments  were  also  made  with  the  same  results  in  which,  after 
Cohn,  ammonium  tartrate  was  employed  along  with  starch  as  a 
nutrient  medium  for  the  bacteria,  with  the  result  that  so  long  as  even 
a  trace  of  this  salt  was  present  with  the  starch,  the  latter  was  not 
attacked  by  bacteria  in  the  slightest  degree,  but  on  its  disappearance, 
appearances  of  solution  became  at  once  visible  in  the  starch  granules. 
Another  point  was  also  established  in  the  course  of  these  experiments, 
that  if  air  is  excluded,  no  appearances  of  corrosion  or  solution  of  the 
starch  granules  are  manifested. 
Other  researches  were  made  to  answer  the  problem  as  to  whether 
the  nature  of  this  action  of  bacteria  on  starch  was  such  that  an 
unformed  ferment  analogous  to  diastase  was  secreted  by  those  organ- 
isms to  which  the  corrosive  appearances  may  be  ascribed,  these  being, 
as  already  stated,  precisely  similar  to  the  resulting  action  of  diastase 
itself. 
That  the  starch  in  the  process  became  changed  in  part  to  glucose 
was  easily  ascertained  by  testing  with  Fehling's  solution,  and  a 
detailed  series  of  experiments,  made  with  a  view  of  eliminating' if 
possible  the  ferment  itself,  yielded  evidence  showing  that  bacteria 
possess  the  remarkable  property  of  producing  a  starch-transforming 
ferment  only  when  no  source  of  carbon  other  than  starch  is  at  their 
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