XIV 
Index 
Figures. 
also shows the difference in zonation produced by the difference in thickness 
(Chaudhuri). 
5. Curves showing the relative area (diameter in mm. squared) covered by the mycelium 
at 21 0 C. and 25°C. in agar cultures of Coon’s medium, full strength (N/i), half 
strength (N/2), and quarter strength (N/4) (Chaudhuri) . 
6. Curves showing the relation between the daily increase in dry weight of V. albo- 
atrum in Coon’s liquid medium, and the daily increase in ‘ spread’ of the myce¬ 
lium on the same medium with the addition of agar (Chaudhuri) . 
7. Graph showing the increase in mycelial ‘ spread ’ obtained by measuring diameters 
daily up to ten days at different temperatures (Chaudhuri) .... 
8. Photographs of cultures of V. albo-atrum after fifteen days at 12 0 , 14 0 , 16 0 , 18 0 , 21 0 , 
22*5°, 25 0 , and 27°C. (Chaudhuri). 
9. Dry-weight production of V. albo-atrum in aerated and non-aerated cultures in 
Coon’s medium (Chaudhuri) ......... 
10. Ditto in aerated and non-aerated Coon’s medium of normal strength (N/i), and in 
non-aerated Coon’s medium of half strength (N/2) (Chaudhuri) 
11,12. 11. Two cultures of V. albo-atrum on Coon’s medium plus agar. 12. A culture of 
V. albo-atrum on corn-meal agar at 25 0 C. ; zonation is clearly visible (Chaud¬ 
huri) .. ............ 
1-5. 1. Cell from the cotyledonary parenchyma mounted ‘dry’. 2. The same cell 
irrigated with tap-water, showing the emulsoid phase of precipitation. 3—5. Cells 
showing variations in the final phase of precipitation (Holden and Bexon) 
6. Transverse section of a portion of the upper end of the hypocotyl of a very young 
seedling before the radicle has penetrated the testa (Holden and Bexon) 
7-21. 7-13. Series of semi-diagrammatic figures, showing the behaviour of the vascular 
strands during the transition from the cotyledons to the younger part of the root. 
11 and 12 are from sections below the collet, and illustrate the leisurely manner 
in which root structure is attained. 14-21. 14. Young seedling from which the 
sections illustrated in 15-21 were drawn. 15. Cotyledonary midrib. 16. Bifur¬ 
cation of midrib. 17. Isolated protoxylem and one diagonal bundle at the top 
of the hypocotyl. 18. Portion of section from the middle of the hypocotyl: 
the xylem of the diagonal bundle has divided into two. 19-21. Successive 
stages in the formation of the cotyledonary root pole. 21 is near the lower limit 
of differentiation (Holden and Bexon) ........ 
22. Transverse section of the midrib of the cotyledon when completely unrolled (Holden 
and Bexon). 
23-6. Camera lucida outlines of hypocotyls from'progressively older seedlings. 23 is from 
a seedling in which the cotyledons are just fully expanded ; 24, from one in which 
epicotyledonary growth has commenced ; 25, from one in which the first epico- 
tyledonary leaves are expanded ; 26, from one in which the secondary pair of 
epicotyledonary leaves are expanded (Holden and Bexon) .... 
27-9. 27. Sub-epidermal formation of cork in the hypocotyl: the granular contents of three 
outer cells only shown. 28. Pericyclic cork formation in the region of the collet 
involving more than one layer of cells. Immediately outside these is a layer of 
crushed and disorganized cells, and beyond these the dead outer cortical tissues. 
29. Pericyclic cork formation in the root. The layer of solid black indicates the 
same region as in 28 (Holden and Bexon). 
30-5. Diagrammatic figures illustrating the building up of the petiolar vascular system. 
35 A, B, c show the common variants derived from 34. The bundles a and b 
are lateral bundles which may undergo displacement near the base of the lamina, 
and d and e are portions of the adaxial bar which may undergo similar 
alterations in position : the bundle x is one which is occasionally displaced at 
a higher level (Holden and Bexon) . . 
3 ^ _ 49 * 36 - 4 2 * Camera lucida outlines of successively'lower sections through the young 
plumular bud, showing the simplest type of bundle fusions occurring at the base 
of the petiole (36-40) and the passage into the epicotyl of the three bundles from 
PAGE 
525 
526 
529 
530 
531 
532 
533 
536 
572 
574 
575 
577 
578 
579 
580 
