X 
Index . 
Figures. 
5 - 
6 . 
7* 
8,9. 
2, 3- 
4 - 
5 - 
6. 
7 - 
8 . 
9 - 
10. 
11. 
12. 
13. 
14. 
PAGE 
A. Three longitudinal sections of an embryo in which the basal wall is no longer 
certainly visible. R. Young embryo showing the basal wall clearly, c. Three 
transverse sections of a young embryo (Campbell) ...... 448 
A. Nearly median section of a large embryo showing the initial of the root and the 
apical meristem. B. The apical meristem from another section of the same 
embryo (Campbell) .......... . 449 
A. Nearly median section of a young sporophyte, in which the root has just emerged. 
b. Apex of the stem. c. Apex of second leaf (Campbrll) .... 450 
8. Two sections of the sporophyte shown in Plate XVI, Fig. 16. 9. a. Another 
section of the same sporophyte as in Fig. 8, showing the approximation of the 
xylems from the first and second roots, b. Another section showing the com- 
plete fusion of the xylems. c. Section of the first root showing single xylem. 
D. The same near the base, showing two very unequal xylems (Campbell) . 452 
A. Median section of the apex of the third root. B. Cross-section of the bundle of 
the second root (Campbell) 453 
Age frequencies of flower-buds and bolls of Group I at shedding (Mason) . . 459 
2. Showing weekly changes in mean age in days of flower-buds and bolls of 
Group I at shedding. 3. Rates of flower-bud and boll shedding, flower pro- 
duction, evaporation, and rainfall. Group I (Mason) 460 
Rates of boll-shedding, flower production, evaporation, and rainfall. Group II 
(Mason) . 461 
Percentage of flowers produced daily which were subsequently shed, and daily 
growth-rates of main axis. Groups I and II (Mason) ..... 463 
Daily rates of boll-shedding, rainfall, evaporation, and evaporation due to solar 
radiation. Group I (Mason) 465 
Ditto. Group II (Mason) 466 
Daily rates of flower-bud and boll shedding, axis elongation, evaporation, and rain- 
fall. Group I (Mason) 469 
Daily growth-rate of four groups of plants. Evaporation and rainfall (Mason) . 471 
Day and night growth-rates brought to a 24-hour basis, ratio growth-rate, 
evaporation, and rainfall. Group II (Mason) ....... 473 
Showing the two stages in the growth of a boll (Mason) 474 
Showing recovery in the growth-rate of the boll due to stimulus of fertilization 
(Mason) 475 
Growth-rate of boll, evaporation, and rainfall (Mason) ..... 478 
Daily growth-rates of boll for six days. Coefficients of variability of daily growth- 
rates and daily rate of shedding for Group II (Mason) ..... 479 
Apparatus for measuring growth in volume of roots (Priestley and Pearsall) . 486 
1. Transverse section through the middle of the third internode of a stem over 
a centimetre in diameter, showing the irregular formation of secondary wood. 
2. Same region of a young stem (Thoday) 489 
Parts of Figs. 1 and 2 enlarged (Thoday) . . . . . . . 491 
Sections in the region of transition to two-fifths phyllotaxy of two stems of different 
age drawn to the same scale (Thoday) 493 
(1) to (8) Sections of a median leaf-trace bundle at right angles to its course from 
the leaf- base through the node, showing accompanying phloem strands, which 
form a plexus on each side in the node, connecting with the phloem of adjoining 
bundles. (9) A lateral trace bundle entering at the node showing similar features 
(Thoday) . 495 
Corresponding portions of three sections, each including the three bundles of a leaf- 
trace, at different levels near the apex of a vigorous plant not yet beginning to 
flower (Thoday) 497 
a. Xylem and parts of adjoining tissues of a young bundle near the apex of the 
same plant as Fig. 6, showing ‘ cambial ’ origin of protoxylem. b. Same bundle 
on a smaller scale, c. Young median trace bundle just above the cotyledons, 
