Vernalization 



AND PhOTOPERIODISM 



Plate 5 

 to face p. 42 



Fig. 1.^ — Original Maryland Mammoth tobacco plants with which photupti imliMn was discovered. 

 Plant on left grew in unlishted greenhouse (short days). Plant on right grew in electrically lighted 

 greenhouse (long days). Winter. 1919.^ — Photo by Garner and Allard. 



I- H.. 1.- -Original Biloxi soybean plants with which 

 photoperiodism was first demonstrated. Vegetative 

 plants on left grew outdoors under natural long days. 

 Reproductive plants on right grew outdoors under arti- 

 ficially shortened 10-hour days. Summer, 1920. — Photo 

 by Garner and Allard. 



