DEVELOPMENT. 1 1 1 



layers of meristem cells ; immediately back of these, large intercellular 

 spaces abound. The epidermis of the primary and early adventitious 

 roots differs from all mature rootage in having a copious supply of root- 

 hairs (Fig. 49, 2, 5). It will be recalled that root-hairs are generally said 

 to be wholly lacking in Nymphaea, Nuphar, Euryale, and Victoria. As we 

 have observed them in N. dcntata, lotus, caerulca, zanzibariensis, amazonum, 

 elegans, odorata, capensis, and hybrids, they are doubtless universal in the 

 genus. On one occasion also they were found on early roots of a plant 

 springing from a tuber of N. caerulea. Victoria lacks them even on the 

 primary root. The epidermal cells of the early roots (in N. dcntata] are 

 long and rectangular in surface view, and about as deep as wide ; where 

 root-hairs occur, however, they spring from cubical cells. No shedding of 

 epidermis occurs in these roots. The root-cap is long and thimble-shaped. 

 Inside the epidermis there are in the primary root about six layers of 

 thin-walled cortex cells and a small (diarch ?) vascular bundle. The 

 adventitious roots are like this, but successively larger. In the earliest of 

 these the diarch bundle is quite plain and is surrounded by a distinct 

 endodermis ; the two xylem patches are continuous across the middle of 

 the bundle. The appearance of the central vascular strand of the hypo- 

 cotyl and lower part of the epicotyl is exactly the same as this, but it is 

 described here as " two opposite bundles with their xylems confluent " 

 (cf. Gwynne-Vaughan, 1897). A short process of procambial cells extends 

 toward the base of each cotyledon, but no vascular tissue extends into 

 them. They are composed of elongated thin-walled cells, and have a 

 rather narrow insertion. The bundles of the stem are turned with their 

 sides toward the cotyledons, i. e., a line connecting the bases of the coty- 

 ledons would pass through the confluent xylem and between the phloem 

 masses. Higher up in the epicotyl the two bundles become more distinct, 

 and each, instead of being semicircular in section, is nearly round ; the 

 xylems are still in contact, though torn asunder to leave an irregular air- 

 canal in the middle. The first two leaves are placed opposite the phloems 

 of the two bundles and at their point of insertion the vascular system 

 spreads out toward them on each side. In close succession the bundles 

 of the first adventitious root, the acicular leaf, the first broad leaf, and the 

 second root and broad leaf join the widened portion of the system, with 

 anastomoses across from bundle to bundle. Each of the above-named 

 organs has a single bundle. No central strands exist above this, but the 

 bundles spread out through the now fleshy stem on their way to the 

 various organs. The communication from vessel to vessel which easily 



