i86 
Notes  on  Ginger-Beer  Plant. 
Am.  Jour.  Pharm. 
March.  1920. 
looked  by  busy  pharmacists,  but  the  brief  summary  of  Dr.  Marshall 
Ward's  researches  given  by  Prof.  Reynolds  Green  in  his  work  on 
''Fermentation"  (p.  321)  should  not  have  escaped  notice,  except 
for  the  fact  that  Prof.  Green  did  not  provide  an  alphabetical  index 
to  his  otherwise  excellent  publication.  The  same  fault  applies  to 
Salter's  translation  of  D.  L.  Lafar's  "Technical  Mycology,"  in 
which,  on  pp.  256-267,  illustrations  of  the  two  chief  constituents 
of  the  ginger-beer  plant  are  taken  from  Dr.  Marshall  Ward's  paper. 
Both  these  two  last-named  works  are  in  the  library  of  the  Pharma- 
ceutical Society. 
It  may,  however,  serve  a  useful  purpose  if  a  summary  of  all 
that  is  at  present  known  concerning  the  life-history  of  the  ginger- 
beer  plant  be  placed  on  record  in  the  pages  of  the  Journai^  for  future 
reference. 
In  appearance  the  ginger-beer  plant  bears  some  resemblance  to 
pearl-barley  that  has  been  boiled,  but  the  nodules  vary  in  size  from 
that  of  a  pinhead  to  nearly  an  inch  in  diameter  (see  Fig.  i).  It 
belongs  to  a  class  of  symbiotic  ferments  in  which  a  yeast  and  a 
bacterium  live  together,  the  one  assisting  in  and  promoting  the  work 
of  the"  other.  To  this  class  belong  also  kephir,  the  ferment  of  koumiss, 
and  a  ferment  found  on  the  sugar  cane  in  Madagascar.  The  first 
is  used  in  the  fermentation  of  cow's  milk  in  the  Caucasus,  and  the 
second  in  the  fermentation  of  mare's  milk  in  the  steppes  of  South- 
west Siberia.  The  ginger-beer  plant  and  the  Madagascar  ferment 
can  ferment  saccharose,  maltose,  glucose  and  fructose,  but  not 
lactose.  In  this  particular  feature  they  differ  from  the  kephir  and 
koumiss  ferments,  which  can  split  up  lactose.  Kephir  and  the 
Madagascar  ferment  both  have  a  similar  appearance  to  the  ginger- 
beer  plant,  but  the  koumiss  ferment  is  not  used  in  a  separate  state, 
a  portion  of  fermented  milk  being  added  to  some  fresh  milk  when 
required.  The  products  of  fermentation  are  chiefly  alcohol,  carbonic 
acid  and  some  lactic  and  acetic  acids,  and  in  the  case  of  the  Madagas- 
car ferment  some  succinic  acid,  the  acetic  acid  being  formed  directly 
from  the  sugar,  and  not  through  the  medium  of  the  alcohol. 
When  a  few  pieces  of  the  ginger-beer  plant  are  put  in  a  10-30 
per  cent,  solution  of  cane  sugar  and  the  bottle  put  in  a  warm  place 
fermentation  takes  place  in  about  twenty-four  hours  and  the  liquid 
is  then  observed  to  become  turbid,  and  bubbles  of  gas  begin  to 
ascend.  This  turbidity  is  due  almost  entirely  to  the  yeast-cells 
which  are  shed  from  the  nodules  of  the  plant,  which  rise  and  fall 
