(Intraxylary ) Phloem in the Stems of Dicotyledons /. 587 
of vascular fomdles of which the xylem exists entirely, or for the most 
part, on the outer side. 
5. Distinct vestiges of a medullary system of bundles, having the 
form sometimes of vascular bundles, sometimes of phloem-strands, have 
been found in the peduncle and the node of certain genera. 
Fig. 9. Portion of transverse section of more primitive type of axis (e. g. peduncle of Ecballium ), 
showing the inversely-orientated collateral bundles from which the internal-phloem strands have been 
derived ( ipb ); a scattered system of bundles in four series, sc. ~ sclerotic ring. (Diagrammatic.) 
Fig. 10. Portion of transverse section ot the theoretical ancestral type of stem from which that 
of Cucurbitaceae is presumably derived. The series of internal-phloem bundles (numbered as in Fig. 9) 
are here in their proper place. The innermost series are completely amphivasal. sc. = sclerotic 
ring. (Diagrammatic.) 
6. The bundles or strands composing this system, on being traced 
upwards or downwards, either arise de novo or fuse with the internal- 
phloem strands ; in'any case, the vast majority unite with the latter during 
some part of their course. 
