L\'OH: OBSERVATIONS ON EMBRYOGENY OF NELUMBO. 649 



The integuments of the ovule keep pace with the growth of the 

 embryo and form the thin testa of the seed which lines the thick 

 pericarp. 



4. Fate of the Endosperm. The endosperm reaches its max- 

 imum growth early in Stage C when it forms a considerable 

 mass of tissue lying between the lobes of the cotyledon (Fig. 

 16). The cell walls are never firm and offer little resistance 

 to the growing plumule which forces its way into the center of 

 the mass. The nuclei soon after begin to disappear and the 

 cells to lose their definite outline. The resulting debris is 

 crowded around the plumule by the growth of the cotyledonary 

 lobes and is apparent in the seed as a colorless structureless 

 sheath nearly or quite surrounding the plumule. 



5. The Embryo of the Seed. A earful study of the embryo 

 of the seed without reference to its development brings to light 

 many conditions not to be found in a dicotyledonous seed. The 

 lobes of the cotyledon are not separate structures, but have a 

 common tissue at the base of the embryo upon which the plu- 

 mule stands (Figs, n, 22). The sinuses between the lobes are 

 not of equal depth, the front sinus being deeper than the rear, 

 so that the common tissue of the lobes (3, Fig. n) extends 

 higher up in the rear of the plumule than it does in front of it. 

 This peculiarity is even more noticeable in the seed of N. 

 nelumbo than in that of N. lutea illustrated in the figure, and it 

 is so distinct that it is remarkable that it has not been described 

 before. The radicle is to a greater or less extent imbedded in 

 tissue of cotyledonary origin, in this respect conforming to well- 

 known monocotyledonous types. 



THE EMBRYOGENY OF NELUMBO COMPARED WITH THAT 

 OF OTHER MONOCOTYLEDONS. 



In its early development the embryo of Nelumbo is strikingly 

 similar to that of Pistia described by Hegelmaier ('74, 68 1- 

 686. pi. ii .Jig. 4.5-52}. The oosperm of Pistia, Hegelmaier 

 finds, does not cut off a suspensor cell but by uniform divisions 

 builds up a spherical embryo as in Nelumbo. The bifurcation 

 of the cotyledon is not so inexplicable a deviation from the or- 

 dinary course of development as it may at first appear. It is 

 rather to be considered as a modification brought about through 

 the adaptation of the embryo to the available space within its in- 

 vestments. 



