Cockayne. — Development of Seedlings. 289 



increase in size, until the leaf finally attains to the form shown 

 in fig. 27. The 2nd pair of leaves are at first quite sessile and 

 linear ; as they become broader they are raised from between 

 the protecting petioles of the 1st pair of leaves by their own 

 petioles lengthening, which now, in like manner, protect the 

 developing 3rd pair of leaves. At this stage the 2nd and 3rd 

 internodes are hardly visible. After three months' growth 

 the tallest seedling was 6 mm. above the ground, with two 

 pairs of fully developed leaves, and the 3rd pair in process of 

 development. After twelve months' growth a young plant is 

 28 cm. tall, with a root 68 cm. in length. This latter would 

 probably have been longer had the pot been deeper. It has 

 seventeen pairs of leaves, all of which are petiolate, very 

 deeply toothed or pinnatifid, one lateral shoot from the axil of 

 one of the 2nd pair of leaves, and three lateral shoots, with 

 each one pair of leaves, from the axils of leaves near the apex 

 of the main shoot. The leaf-blades are nearly all horizontal, 

 but the upper ones point slightly upwards, and the lower ones 

 are bent slightly downwards, in order to accommodate them- 

 selves to the light-supply. 



Plant 6 mm. tall with two pairs of fully developed leaves. 



Primary root 3 cm. long at least, pale-coloured, slender, 

 with many lateral rootlets. It is very difficult to dig up a 

 seedling without breaking the root. 



Hypocotyl 4 mm. or 5 mm. in length, erect, stout, terete, 

 glabrous, green or slightly tinged with red. 



Cotyledons 4mm. x 2 mm., ovate, entire, obtuse, glabrous, 

 soft and rather succulent ; petioles flattened above, half the 

 length of lamina, inserted at about angle of 45°, connate at 

 base. 



1st pair of leaves variable in shape and size, 4 mm. or 

 5 mm. long x 2 mm. to 275 mm. broad, ovate or oblong-ovate, 

 rounded or cuneate at base, fleshy, green, toothed rather 

 deeply with one or two teeth on each side ; petioles two- 

 thirds the length of lamina, flattened and slightly channelled 

 above, connate at base ; midrib more or less raised on under- 

 surface of leaf. 



2nd pair of leaves very similar to 1st pair, but very deeply 

 toothed w T ith two or three teeth on each side, or almost pin- 

 natifid. 



Stem green, very soft and juicy, hardly developed except 

 for 1st internode, bifariously pubescent ; 1st internode 1 mm. 

 in length or a little longer. 



General description of a seedling leaf (figs. 28, 29, 35) : 

 From lanceolate to ovate or ovate-oblong in outline, often 

 cuneate at base, usually very deeply toothed with one, two, or 

 three teeth on each side, at times almost pinnatifid (fig. 35) ; 

 acute, glabrous, usually bright-green on both surfaces of 

 19 



