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  Microsporogenesis 
  in 
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   29: 
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  pi. 
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  7. 
  Guignard, 
  M. 
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  La 
  doable 
  fecondation 
  chcz 
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  Solances. 
  

  

  Jour, 
  de 
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  16: 
  1-23. 
  1902. 
  

  

  8. 
  Juel, 
  H. 
  O. 
  Untersuchungen 
  iiber 
  die 
  Auflosung 
  der 
  Tapetenzellen 
  

  

  in 
  den 
  Pollensacken 
  der 
  Angiospermen, 
  jahrb. 
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  337-364. 
  pl^ 
  4^ 
  5- 
  I9i5< 
  

  

  9. 
  Mottier, 
  David, 
  M. 
  The 
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  r 
  

  

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  pi. 
  27, 
  28. 
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  10. 
  . 
  Beitrage 
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  Kenntniss 
  der 
  Kerntheilung 
  in 
  den 
  Pollen- 
  

  

  mutterzellen 
  einiger 
  Dikotylen 
  und 
  Monokotylen. 
  Jahrb. 
  

   Wiss. 
  Bot. 
  30: 
  169-204. 
  1897. 
  

  

  11. 
  Nothnagel, 
  Mildred. 
  Reduction 
  divisions 
  in 
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  pollen 
  mother 
  

  

  cells 
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  Allium 
  tricoccum. 
  Bot, 
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  61: 
  543-476. 
  pL 
  28-jo. 
  

   1916. 
  

  

  12. 
  Payne, 
  Fernandus, 
  Chromosomal 
  variation 
  and 
  the 
  formation 
  of 
  

  

  the 
  first 
  spermatocyte 
  chromosomes 
  in 
  the 
  European 
  earwig, 
  

  

  -J 
  

  

  Forficiila 
  sp. 
  Jour. 
  Morph. 
  25: 
  559-581. 
  pi. 
  7, 
  2, 
  1914. 
  

  

  13. 
  Pickett, 
  F, 
  L. 
  Wandering 
  tapetal 
  nuclei 
  of 
  Arisaema, 
  Am. 
  

  

  * 
  

  

  Jour. 
  Bot. 
  3: 
  461-469. 
  pL 
  20 
  -j-f.i-S. 
  1916. 
  

  

  14. 
  Schafifner, 
  J. 
  H. 
  Reduction 
  division 
  in 
  Agave, 
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  198-214. 
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  12-14. 
  1909. 
  

  

  Hseplanation 
  of 
  plates 
  S 
  and 
  9 
  

  

  All 
  figures 
  X 
  2270. 
  

  

  Fig. 
  I. 
  A 
  pollen-mother 
  cell 
  in 
  resting 
  condition. 
  

  

  Fig. 
  2. 
  An 
  early 
  presjoiapsis 
  stage. 
  

  

  Fig. 
  3. 
  A 
  stage 
  a 
  little 
  later 
  than 
  that 
  shown 
  in 
  Fig. 
  2. 
  

  

  Fig. 
  4. 
  Synapsis. 
  

  

  Fig. 
  5, 
  Coming 
  out 
  of 
  synapsis. 
  

  

  Fig. 
  6. 
  An 
  early 
  hollow 
  spirem 
  stage. 
  

  

  FiG. 
  7. 
  Segmentation 
  in 
  process 
  showing 
  method 
  of 
  cutting 
  olT 
  the 
  bivalents. 
  

  

  Fig. 
  8. 
  A 
  stage 
  a 
  little 
  later 
  than 
  that 
  shown 
  in 
  Fig. 
  7. 
  

  

  Fig. 
  9. 
  Segmentation. 
  

  

  Fig. 
  10. 
  Some 
  of 
  the 
  shapes 
  assumed 
  by 
  the 
  bivalents. 
  

  

  Fig. 
  II. 
  A 
  spirem 
  stage 
  in 
  which 
  the 
  double 
  nature 
  of 
  the 
  thread 
  is 
  shown. 
  

  

  Fig. 
  12. 
  A 
  bipolar 
  spindle, 
  passing 
  into 
  anapha^. 
  

  

  Fig. 
  13. 
  A 
  metaphase, 
  polar 
  view, 
  showing 
  the 
  twelve 
  bivalents. 
  

  

  Fig. 
  14. 
  A 
  telophase. 
  

  

  Fig. 
  15. 
  A 
  little 
  later 
  stage, 
  in 
  which 
  the 
  double 
  nature 
  of 
  the 
  chromosomes 
  is 
  

  

  shown. 
  

  

  Fig. 
  16. 
  An 
  early 
  multipolar 
  spindle 
  of 
  the 
  second 
  division, 
  showing 
  the 
  clump- 
  

   ing 
  of 
  the 
  chromosomes. 
  

  

  Fig. 
  17. 
  A 
  stage 
  a 
  little 
  later 
  than 
  that 
  shown 
  in 
  FiC 
  16. 
  

   Fig. 
  iS. 
  Telophases 
  of 
  the 
  second 
  division. 
  

  

  