576 IVorsdetl. — The Origin and Meaning of Medullary 
ment of the rays. Three of these bundles were traced downwards; from 
one of them, whose xylem was directed outwards , three or four minute 
phloem-strands became separated off, which eventually fused with an 
internal-phloem group. The bundle itself fused with one of two 
bundles lying opposite the adjoining ring-bundle, the product of fusion 
farther down fusing with this ring-bundle, i. e. with its internal phloem ; 
the remaining one of the two bundles just mentioned dwindled greatly 
Fig. i. Cucurbita Pepo . The vascular tissue of the fruiting peduncle, in transverse section, 
showing scattered and independent internal-phloem strands and bundles ; the latter variously 
orientated, and one or two with amphivasal structure, rb , vascular bundle of the normal ring; 
ip , internal phloem ; ipb , medullary bundle or bundle of abnormal ring, homologous with ‘ internal 
phloem’, x n. 
in size, and finally appeared to die out so close to the large internal-phloem 
group that it practically amounted to a fusion therewith. 
Another small inverted medullary bundle, on being traced downwards, 
was seen to fuse with the internal-phloem group opposite to it; after 
the fusion the xylem of the former occupied a lateral position in the result** 
ing large phloem-group ; farther down it appeared embedded in the middle, 
remaining so as far as it was traced, so that the phenomenon occurred of 
an internal-phloem group with central xylem. 
In another fruit-peduncle there were one or two rings of large bundles 
