﻿1 
  890. 
  J 
  BOTANICAL 
  GAZETTE 
  

  

  207 
  

  

  markets 
  a 
  ferment 
  is 
  made 
  from 
  potatoes, 
  boiled 
  and 
  mashed, 
  

   with 
  flour, 
  salt, 
  sugar, 
  the 
  water 
  that 
  the 
  potatoes 
  have 
  been 
  

   boiled 
  in, 
  and 
  yeast. 
  There 
  are 
  various 
  other 
  methods 
  of 
  

   makmg 
  this 
  ferment, 
  but 
  they 
  do 
  not 
  differ 
  essentially 
  from 
  

   one 
  another. 
  This 
  is 
  sometimes 
  called 
  emptying^, 
  or 
  ju^r- 
  

   yeast, 
  and 
  is 
  semi-liquid, 
  so 
  that 
  it 
  differs 
  very 
  materialfy 
  

   from 
  the 
  leaven 
  of 
  the 
  old 
  country. 
  Of 
  course, 
  m 
  towns 
  and 
  

   cities 
  where 
  a 
  fresh 
  supply 
  of 
  yeast 
  can 
  be 
  obtained 
  readily 
  

   no 
  such 
  methods 
  need 
  be 
  resorted 
  to. 
  Besides 
  the 
  ferments 
  

   mentioned 
  there 
  are 
  also 
  the 
  dry 
  yeast 
  cakes, 
  that 
  is, 
  veast 
  

   mixed 
  with 
  corn-meal, 
  and 
  dried, 
  which 
  will 
  vegetate 
  when 
  

   moistened, 
  and 
  the 
  salt-rising 
  where 
  no 
  ferment 
  is 
  added, 
  

   the 
  fermentation 
  being 
  supposed 
  to 
  be 
  set 
  up 
  by 
  the 
  organ- 
  

   isms^that 
  are 
  already 
  in 
  the 
  ingredients. 
  

  

  1 
  he 
  experiments 
  which 
  I 
  performed 
  in 
  order 
  to 
  determine 
  

   whether 
  the 
  yeast 
  or 
  the 
  bacteria 
  are 
  more 
  instrumental 
  in 
  

   causing 
  bread 
  to 
  rise 
  do 
  not 
  solve 
  the 
  question 
  by 
  any 
  means, 
  

   still 
  they 
  give 
  some 
  additional 
  information 
  on 
  the 
  subject, 
  

   rreshly 
  made 
  dough 
  that 
  had 
  been 
  fermented 
  with 
  Vienna 
  

   pressed 
  yeast, 
  commonly 
  called 
  German 
  yeast, 
  and 
  sold 
  un- 
  

   fier 
  the 
  name 
  of 
  Fleischmann's 
  Compressed 
  Yeast, 
  was 
  ex- 
  

   amined 
  with 
  the 
  microscope 
  and 
  the 
  j^east 
  found 
  to 
  be 
  

   oaccharomyces 
  cerevisiee, 
  and 
  with 
  it 
  a 
  bacterium 
  having 
  the 
  

   characteristics 
  of 
  Bacillus 
  subtilis. 
  These 
  two 
  germs 
  were 
  

   separated 
  from 
  each 
  other 
  by 
  means 
  of 
  gelatine 
  plate-cul- 
  

   ures. 
  A 
  single 
  colony 
  of 
  each 
  was 
  placed 
  in 
  flasks 
  in 
  equal 
  

   quantities 
  of 
  a 
  nutrient 
  solution 
  made 
  according 
  to 
  directions 
  

   given 
  by 
  Dr. 
  Stone, 
  ^^ 
  the 
  proportions 
  being 
  25 
  grams 
  Ger- 
  

   "lan 
  yeast 
  to 
  125 
  cubic 
  centimetres 
  distilled 
  water, 
  with 
  10 
  

   per 
  cent, 
  sugar, 
  boiled 
  thoroughly, 
  filtered, 
  and 
  sterilized 
  for 
  

   mree 
  successive 
  days. 
  The 
  flasks 
  containing 
  the 
  yeast 
  and 
  

   f 
  "^'■^"^ 
  were 
  then 
  placed 
  in 
  a 
  vegetation 
  chamber, 
  kept 
  at 
  

   aoout 
  84-86° 
  F. 
  (29-30° 
  C), 
  this 
  being 
  the 
  optimum 
  temper- 
  

   (5^op 
  ^" 
  Bacillus 
  subtilis, 
  that 
  of 
  yeast 
  being 
  about 
  92° 
  F. 
  

   ^33 
  ^.). 
  After 
  vegetating 
  for 
  two 
  and 
  one-half 
  months 
  they 
  

  

  e-f^K 
  ^T^^^ 
  ^°^ 
  ^^^^ 
  amount 
  of 
  carbon-dioxide 
  given 
  off 
  by 
  

   ^ach, 
  the 
  gas 
  that 
  had 
  accumulated 
  in 
  the 
  flasks 
  being 
  first 
  

  

  th^h^^^*- 
  '^^^ 
  y^ast 
  gave 
  off 
  23 
  mg. 
  gas 
  in 
  one 
  hour, 
  

   mifl 
  ^^f^"^ 
  70 
  mg. 
  in 
  the 
  same 
  time. 
  A 
  second 
  test 
  was 
  

   2ro 
  1? 
  ^ 
  ^^^^ 
  ^^y^' 
  growth 
  of 
  each, 
  the 
  germs 
  for 
  these 
  

   WJ 
  f 
  ^^'^^g 
  obtained 
  from 
  agar 
  cultures 
  of 
  each, 
  inocu- 
  

   -o 
  m 
  ^^^ 
  ^^^ 
  original 
  plate 
  cultures. 
  The 
  yeast 
  gave 
  off 
  

   ^._^i^5:^Jhe^bacteria 
  60 
  mg. 
  in 
  an 
  hour. 
  In 
  a 
  case 
  where 
  

  

  ^^' 
  W. 
  E., 
  BoT. 
  Gazette, 
  1887, 
  p. 
  270. 
  

  

  