ON THE IDENTIFICATION OF THE VARIOUS STRUCTURES IN THE YEAST CELL

Abstract

1. The  nucleus  of  yeast  could  be  fixed  and  stained  selectively.  The  vacuoles  are  neo-formations.  The  vacuolar  colloids  often  condense  into  granules  which  are  transitory.  This  phenomenon  could  be  accentuated  by  vital  staining.
2. The  centrosomes  are  identified  purely  on  their  position  and  role  in  the  organization  of  the  achromatic  spindle.  Available  evidence  suggests  that  the  centrioles  are  not  Feulgen  positive.
3. The  structure  and  behaviour  of  the  nucleus  of  differentiated  cells  of  higher  organisms  are  entirely  different  from  those  of  embryonic  cells.  The  radically  different  reactions  occurring  in  yeast  under  aero- and  anaerobiosis  render  it  essential  to  treat  the  cytological  pictures  observed  in  these  two  phases  separately.
4. Actively  dividing  yeast  cells  in  well  aerated  media  show  a  homo- geneous  cytoplasm  with  no  vacuoles  or  granules.  The  complete  mitotic  cycle  could  be  mapped  out  by  smearing  at  regular  intervals  samples  from  aerobic  cultures.
5. Photomicrographs  are  presented  showing  the  two  chromosomes  orientated  on  a  spindle  which  has  at  its  poles  the  centrioles  with  centro- spheres.  The  centrosomes  are  not  found  in  all  the  cells.