\'ernalization 



AND PhOTOPERIODISM 



Plate 3 



to face p. 26 



V. G. Gregory, distinguished British plant physiolo- 

 sist. of the Imperial College of Science and Technology, 

 Lnndon. — Photograf>li by J. Russe/l & Sons. 



O. N. Purvis of the Imperial College of Science and 

 Technology. London.- l^hotofiraph by E. C. Thompson. 



