TAG VON 5-7 Stunden noch 1-2 Stunden Zusatzlicht wah- 



REND DER DUNKELHEIT GEBOTEN WERDEN 173 



Nicotiana tabacum Maryland-Mammut X Java. Verlauf der 



Blute unter naturlichen Tageslangenbedingungen 178 



Nicotiana tabacum Maryland-Mammut X Java. Wuchshohe in 



Beziehung zur Blutenbildung 179 



LIST OF PLATES 



Plate 1. — Portraits of H. A. Allard, A. H. Blaauw, W. W. Garner 

 and N. G. Cholodny facw^f p. viii 



Plate 2.— Portraits of G. Gassner, G. Klebs, T. D. Lysenko and 

 N. A. Maximov facing p. ix 



Plate 3. — Portraits of F. G. Gregory and O. N. Purvis . .facing p. 26 



Plate 4. — Field trials carried out by Gregory and Purvis at East 

 Malling facing p. 27 



Plate 5. — Fig. 1 : Original Maryland Mammoth tobacco plants 

 with which photoperiodism was discovered. — Fig. 2 : Original 

 Biloxi soybean plants with which photoperiodism was first 

 demonstrated facing p. 42 



Plate 6. — Fig. 3: A vegetative Biloxi soybean plant, 42 days old, 

 grown under a long photoperiod. — Fig. 4: A reproductive 

 Biloxi soybean plant, 42 days old, grown under a short photo- 

 period. — Fig. 5 : Close-up of upper part of stem of reproductive 

 plant shown in Fig. 4 facing p. 86 



Plate 7. — Fig. 6 : Section through the apical meristem of a vegeta- 

 tive soybean plant. — Fig. 7 : Section through the apical meri- 

 stem of a reproductive soybean plant. — Fig. 8: Rudbeckia bi- 

 color PLANTS, 86 days old.— Fig. 9: High temperature induced 

 flowering in Rudbeckia bicolor plants grown in a relatively 

 HOT greenhouse facing p. 87 



Plate 8. — Figs. 1-4: Cambial activity in Nicotiana tabacum var. 

 Maryland Mammoth facing p. 94 



Plate 9. — Figs. 5 and 6 : Cross-section of stems of poinsettia. — Figs. 

 7 and 8 : Spodograms of Xanthium facing p. 95 



Plate 10. — Figs. 9-11 : Cross-sections of stems of Biloxi soybean 



jacin-g p. 96 



Plate 11. — Flowering in a winter variety of rice (Rupsail) 



facing p. 122 



Plate 12.— Temperature effects on bud development . . .facing p. 149 



