89 



i 



pericarp either opens by gradual decay or becomes ruptured 

 by the jelly, which, after contact with the water, swells rap- 

 idly and forms a perfectly translucid, mucilaginous coat around 

 the seed (Plate XVII, Fig. 139), very much like the shell of a 

 univalve mollusk, and is only to be removed from the seed 

 with great difficulty. The germination begins wdiile the seed 

 is still floating upon the water, and the first sign of the young 

 plant is the plumule breaking out through the mucilaginous 

 envelope and separating itself from the clasping margins of 

 the cotyledon (Plate XVII, Fig. 141). In this very first state 

 of germination there is to be seen not only the first leaf (L^ 

 in Fig. 141) surrounding the plumule, the position of which 

 is alternating with the cotyledon, but also the primary root 

 (R in Fig. 141), which has commenced to break out Two 

 pairs of other roots are visible on each side of the first root, 

 but merely as round spots, which are lighter colored than the 

 surrounding parts of the seed. The seed now begins to sink 

 in the water, and, while the plumule continues its growth, the 

 roots become more distinct, partly breaking through the still 

 persisting mucilaginous coat. It will be seen by an examina- 



J 



tion of Plate XVII, Fig. 141, in which the same seed, seen 

 from the side and from the front, has been figured, that the 

 primary root is the farthest developed. 



Next in order are the two pairs of roots, mentioned above. 

 The coleorhiza is distinct, but entirely smooth, as the 

 roots themselves, witliout any hairs. Above these roots and 

 at the very base of the plumule one pair of round spots 

 is to be observed, which, as \\ ill be shown later, represent a 

 third pair of roots, but whose development is proportionally 

 very slow. * 



In following the further development of the germinating 

 plantlet, the next state is (Plate XVII, Fig. 144) the disap- 

 pearance of the jelly by gradual solution, till it forms but a 

 thin membrane around the seed, then soon decays and dis- 

 appears entirely. The first leaf now comes out and shows its 

 final form, it being bicarinate, sheathing and scale-like. The 

 form of this first leaf next the scutellum is characteristic of 

 most of the Arace^B with exalbuminous seeds, while in those 



