Vernalization 



AND PhOTOPERIODISM 



Plate 8 

 to face p. 94 



FiGUKES 1-4. — Nicoliaiia tabacuiii vak. MaryUiiui Maiiniinlh : 1, Non- 

 flowering plant in long photoperiods with cool nights and warm days. 2, 

 Flowering plant in short pliotoperiods with cool nights and warm days. 3, 

 Non-flowering plant in long photoperiods with warm nights and cool days. 

 4, Flowering plant in short photoperiods with warm nights and cool days. 

 Cessation of cambial activity precedes blossoming. 



