It  is  a  mistake  to  assume  that  pure  yeast  can  do  every-
thing. On  the  contrary,  it  is  necessary  to  point  out  that  the
requirements  as  regards  the  preparation  of  the  malt,  wort,  &c.,
are  the  same  as  formerly.  If  there  are  defects  here,  the  beer
will  also  be  faulty  even  though  pure  yeast  has  been  employed.
On  the  other  hand,  the  doctrine  more  or  less  openly  expressed
by  some  zymotechnologists,  even  quite  recently,  is  incorrect,
namely,  that  the  fermentation  is  in  the  main  dependent  only
on  the  composition  of  the  wort,  so  that  a  good  malt  always
gives  satisfactory  fermentations,  favours  the  development  of
the  desired  species  of  brewery  yeast  and  checks  the  disease
germs,  whilst  a  bad  malt  on  the  contrary  favours  the  develop-
ment of  the  latter.  The  main  result  of  such  a  doctrine  would
be  that  so  long  as  we  take  care  to  have  a  good  wort  we  do
not  require  to  trouble  much  about  the  character  of  the  yeast.
This,  however,  like  a  great  deal  more  that  has  been  written
on  the  manufacture  of  beer,  even  by  distinguished  authors,
is  only  conjecture  lacking  all  foundation.  Likewise  we  must
not  forget  that  we  have  no  definite  chemical  knoivledge  as  to
what  we  are  to  understand  by  a  good  or  an  inferior  malt,  by
a  good  or  an  inferior  wort.
