Vernalization 



AND PhOTOPERIODISM 



Plate 

 to face p. 95 



Figures S, 6.— Cross-sfxtio.\ of stf.ms of poixsettia { Eiifhorbhi pul- 

 chcrrima) : 5, Non-flowering stem. 6, Flowering stem sampled above a 

 "temperature girdle" has a cambial condition typical of flowering stems. — 

 Figures 7, 8. — Spodograms of Xcvithiiiiii: 7. Ash residue of vegetative stem. 

 8, Same after five short plmtopcriods. 



