AMarT'w3ARM*}        New  Theory  of  Fermentation.  119 
It  is  probable,  M.  Sagot  thinks,  that  the  poison  present  in  the  ma- 
nioc is  an  instable  organic  compound,  hurtful  in  itself,  but  especially 
dangerous  from  the  fact  that,  under  certain  conditions,  it  will  engen- 
der hydrocyanic  acid.  The  leaves  when  bruised  exhale  a  smell  of 
bitter  almonds,  and  the  presence  of  prussic  acid  in  the  roots  has  been 
established.  This  he  considers  to  explain  the  fact  that  while  the  ma- 
nioc water,  especially  when  distilled,  is  very  poisonous,  in  Guiana 
and  Brazil  the  Indians,  after  boiling  it  and  removing  the  scum,  use  it 
as  a  beverage.  Although  wild  animals,  too,  are  sometimes  poisoned 
through  eating  the  leaves,  sometimes  they  are  not ;  this,  he  thinks, 
occurs  when,  a  small  quantity  being  eaten,  the  gastric  juice  exercises 
an  energetic  action  before  hydrocyanic  acid  can  be  developed. 
The  sweet  cassava,  or  Camanioc,  contains  so  small  a  quantity  of 
acrid  principles  that  the  roots  are  cooked  at  a  fire  and  eaten  like  po- 
tatoes. It  is  a  rapid  growing  variety,  becoming  ripe  in  five  or  six 
months,  and  in  two  or  three  months  more  the  roots  become  hard  and 
unfit  to  eat.  The  bark  of  the  stalk  is  white,  the  petioles  of  the  leaves 
are  of  a  fine  purple-red  color,  and  the  luxuriant  leaves  at  the  foot  of 
stalk  are  7-partite.  The  tubercles  are  long  and  of  small  diameter  ; 
when  cooked  in  the  ashes  of  a  fire  they  are  agreeable  to  the  taste, 
sweet  and  of  a  fine  consistence. — Pharm.  Journ.  (London),  Jan.  18? 
1873. 
THE  NEW  THEORY  OF  FERMENTATION. 
The  indefatigable  Pasteur  again  comes  upon  the  stage  with  a  series 
of  experiments  to  prove  the  accuracy  of  his  theory  of  fermentation. 
He  claims  that  grape  juice,  when  exposed  to  the  action  of  the  air,  or 
of  oxygen,  never  of  itself  alone  undergoes  alcoholic  fermentation,  but 
that  this  only  happens  when  those  particles  of  dust,  or  germs  of  fer- 
ment, which  are  present  both  in  the  grape  and  the  woody  stem,  are 
introduced  into  the  must. 
The  method  of  experimenting  is  very  simple  in  theory  and  perfectly 
convincing.    It  is  as  follows  : 
Forty  glass  bulbs  were  taken,  with  tubes  bent  downward  to  prevent 
dust  falling  into  them.  On  the  side  was  a  neck  fitted  with  rubber 
tubing  and  glass  stopper,  through  which  at  a  given  moment  the  mate- 
rial could  be  introduced. 
These  40  bulbs  were  filled  with  an  easily  fermentescible  substance 
which  had  been  previously  boiled,  and  were  divided  into  four  series. 
