322 Shaw.— The Seedling Structure of A ratccaria Bidwillii . 
the hypocotyl. At this level they spread outwards, allowing for the insertion 
of the numerous bundles (c.b.) from the cotyledons (Diagram I, Figs. I, 2). 
The number of bundles (c.b.) entering the hypocotyl from the cotyledonary 
tube is subject to great variation. In the tube itself there are usually from 
12-16 small collateral bundles. These bundles consist chiefly of secondary 
xylem (x.) } the primary xylem (p.x f .) being practically restricted to the 
endarch protoxylem. As the bundles enter the hypocotyl, they become 
associated, sometimes in pairs, sometimes in threes, and these groups pass 
inwards and fuse with the vascular tissue from the plumule (Diagram I, Fig. 3). 
The bundles derived from the cotyledons fuse with those from the shoot to 
form a continuous ring in which it is impossible to discern the limits of the 
vascular tissue from either source (Diagram I, Fig. 4). Lower down, this 
ring breaks up into from 5-7 curved segments (s.), with the concavity out- 
wards, and each segment then divides into two bundles which divaricate and 
approach those derived from adjacent segments (Diagram II, Figs. 5 > 6). 
In this way there arises in the upper portion of the hypocotyl a ring of from 
5-7 pairs of vascular bundles, the two individuals of any one pair being 
inclined towards each other, and originally derived from different segments. 
