464 
Holden and Daniels. — Observations on the 
anomalies in their phloem arrangement, after receiving a number of accessory 
strands, unite in the uppermost third of the hypocotyl (Fig. 25) and, the 
protoxylem becoming exarch, a diarch condition is produced which persists 
throughout the hypocotyl and results in the giving off of two stout lateral 
roots at the point of junction with the tap-root (Fig. 26). Immediately 
Figs. 16-28. Figs. 16-20 ‘Seedling A’, Figs. 21-28 ‘Seedling B ’. Both show a fusion of 
the cotylar midribs, these behaving in transition like a single normal midrib. These and all sub- 
sequent figures are camera lucida drawings reduced to scale. 
below the point of origin of the lateral roots the diarch condition is still 
evident, in spite of a considerable amount of secondary thickening which has 
produced a tracheide complex with a continuous sheath of phloem. At 
a slightly lower level the protoxylem, which is continuous with that of the 
fused laterals, flattens out and bifurcates, the phloem sheath at the same 
time breaking into four parts (Fig. 27). Three of the gaps in the phloem 
are opposite the protoxylems derived from the median and lateral bundles 
