Am.  Jour.  Pharm.| 
February,  1920.) 
Y^east  Growth. 
105 
Medical  Corps,  and  not  an  independent  organization.  This  latter 
has  always  been  understood,  but  the  bill  apparently  did  not  make  it 
entirely  clear.  These  modifications  will  be  brought  out  at  the 
hearings  before  the  Naval  Committee. 
YEAST  GROWTH  AND  ALCOHOLIC  FERMENTATION  BY 
LIVING  YEAST.* 
The  methods  used  by  the  physical  chemist  to  measure  rates  of 
chemical  reactions  can  be  applied  to  investigate  the  process  of  alco- 
holic fermentation  by  living  and  growing  yeast  cells.  The  results 
obtained  in  this  way  are  valuable,  for  they  not  only  give  new  informa- 
tion, but  also  make  is  possible  to  bring  into  line  results  obtained  by 
other  methods.  In  this  communication  yeast  growth  and  alcoholic 
fermentation  are  considered  from  this  point  of  view. 
The  subject  matter  may  be  explained  by  describing  the  growth 
of  yeast  cells  in  a  nutrient  medium,  and  by  pointing  out  the  main 
factors  which  determine  the  rate  of  growth  and  rate  of  fermentation 
at  different  stages  of  the  reaction. 
Number  of  cells  per  Cc. 
Diagram  of  Yeast  Growth. 
A  =  lag  phase  in  growth;  B  =  logarithmic  phase;   C  =  retarded  growth; 
D  =  yeast  crop;  E  =  death  of  yeast  cells. 
If  a  trace  of  yeast  is  seeded  into  malt  wort,  which  is  a  medium 
*  Reprinted  from  Journal  of  Society  of  Chemical  Industry,  Oct.  31,  1919. 
By  Arthur  Slator. 
Time 
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