POLLOCK ON FIBRO-VASCULAR IN ECHINOCYSTIS LOBATA. 41 



as that ill the pi'inuuy root. (Fig'. 1.) The bundles in the hypocotyl 

 hiter become bi-colhiteral by the development of phloem internal to the 

 xylein. 



Above the upper Avhorl of secondary roots at a distance varying 

 from 1 to 1() mm. each of the four collateral (or bi-coUateral) bundles 

 jseparates into two equal parts, making;- eight in all which take up posi- 

 tions at approximately ecpial distances from each other, except that 

 there ai-e two groups of four (Fig. '2). Then higher still in the hypoco- 

 tyl. at opposite points in the circle of eight bundles, two adjacent 

 pairs again unite to form one bundle each (Figs. ;> and 4), making only 

 six in the circle, and this number continues up to the cotyledons. The 

 two bundles formed by the fusion of two pairs are so situated that 

 they would be cut by a plane between the cotyledons splitting the 

 hy}>ocotyl into halves. They correspond therefore to the edges of the 

 hypocotyls of those of the Cucurbitacea^ whose hypocotyls are much 

 more flattened, as Cucurbita pepo and C. maxima. 



The individual bundles that unite in pairs wlien the number is re- 

 duced fi-om eight to six, liave not originated from the same original 

 bundle of the four immediately above the upper roots, but from 

 adjacent bundles of those four as will appear by following through the 

 changes as indicated in figures 1, 2, 3, 4. These figures are diagrams made 

 from actual se<tions, and represent dimensions fairly accurately. Fig 1 

 shows a section above Uie upper whorl of roots, where two of the four 

 bundles first show indications of separating into tw'o each. Fig. 2 

 sliows tlie eight bundles, which are grouped distinctly into two groups, 

 having a definite relation to the longest diameter of the section, which 

 is not exactly circular in outline. Fig. :J shows two pairs of the eight 

 bundles almost fused, and Fig. 4 shows the bundles as they are found 

 in the upper part of the hypocotyl, and through the greater part of its 

 1 en nth. 



Fig. 1. 



Fig. 2. 



Fig. .■!. 



Fig. 4. 



SUMMARY. 



1. Ecliinocystis lobata has no si»ecial organ at the base of the hypo- 

 cotyl to liold the seed coats in germination, but it (h'veloi)S very early 

 in germination two whorls of secondary roots near the top of the pri- 

 marv root. 



2. Only below the second whorl of lateral roots does the primary 

 root shoAv the typical root structure. 

 6 



