Development. 109 



depends upon the depth to which the seeds are buried ; it reaches up just 

 to the surface of the soil. If they are uncovered at the bottom of the 

 water, the epicotyl is scarcely visible (Fig. 49, 3) ; it is about as long as 

 the width of the cotyledonary petioles. In other circumstances this inter- 

 node may be 2.5 cm. long (2, 4, 5). The stimulus which effects this 

 difference is light. Seeds of N. gladstoniana and flava grown in glass 

 bottles of water in the dark sent out very long epicotyls reaching far 

 above the layer of seeds in the bottom of the bottle. The first leaf 

 produced by the seedling is a slender awl-shaped object, like a spear of 

 grass (Tricker, 1897) ; it looks like a prolongation of the epicotyl (Fig. 49, (a); 

 the boundary between the two is marked by a tiny rudiment of the 

 next leaf. While these changes are going on in the plumule, a large tuft 

 of root-hairs is formed on a broad prominence at the base of each cotyle- 

 donary petiole. These hairs serve to anchor the plantlet to the substratum 

 and doubtless to absorb some food during the inactivity of the radicle 

 (Goebel, 1893). After the subulate leaf has nearly reached maturity, and 

 the second leaf-rudiment is swelling, the radicle begins to elongate (Fig. 

 49, 4). Hitherto it has been a tiny papilla between the bases of the cotyle- 

 dons, but it soon grows out into a primary root 5 or 8 centimeters long (5). 



The second leaf of the plantlet arises opposite the first and develops 

 a petiole and an ovate to linear lamina (2, 5). At its base a single adven- 

 titious root comes out and descends into the earth ; it only becomes 

 evident after the leaf is nearly mature (5). Subsequent leaves are broader 

 and broader in the lamina, becoming deltoid in Lotos and cordate to 

 nearly orbicular in Brachyceras (cf. Fig. 50). Several of them remain 

 on short petioles and are typically aquatic, but finally small floating 

 leaves are sent up. Each one bears one or more adventitious roots at 

 the base. The petioles of all the earlier leaves are winged and clasping 

 at the base ; no stipules are developed until later. 



The plantlet being thus pretty well established, the primary root 

 ceases to function and soon dies away. As the nutriment is baled out 

 from the seed, the central portions of the cotyledons are first emptied, 

 then their outer parts, and then the endosperm. Finally the solution of 

 the perisperm begins at the end next to the embryo and works steadily 

 back until the supply is exhausted. The nutriment furnished to the young 

 plant, therefore, is at first highly proteinaceous, and at the last wholly 

 carbohydrate. The cotyledons remain of the same size as before germina- 

 tion, or very nearly so. When the seed has been emptied of its food, the 

 epicotyl shrivels and dies as the primary root did before it (Fig. 49, 1, 6). 



