PLANTS FROM THE SEED. 



77 



the surrounding albumen, which in germination is gradually lique- 

 fied, its starch or amyloid being transformed into dextrine and 

 sugar (80, 82, 83). Thus nourished, the radicle rapidly lengthens 

 into a stem, and develops a root from its 

 lower extremity, connecting it with the 



soil ; and when the enlarging cotyledons 



extricate themselves from the decaying 

 seed-coats and expand in 

 the light as the first pair 

 of leaves, the plantlet is 

 already estabUshed as a 

 complete miniature vege- 

 table, able to nourish it- 

 self, and make sufficient 

 provision for its own con- 

 tinued growth. 



126. The embryo in seeds provided with albumen 

 is sometimes very small, as in Fig. 131, or even 

 much more minute, and with its parts so rudimentary 

 that they are hardly or not at aU discernible previous 

 to their gradual development in germination. But 

 sometimes it is pretty large, and with all its parts 

 129 obvious in the seed; as in the Morning-Glory 



and in Indian Com (Fig. 122). The latter has a highly organized 



FIG. 122. Seed and embryo of the common Moming-Slory, cut across ; the latter seen 

 edgewise. 123. Embryo of the same, detached and straightened, seen flatwise. 124. Germi- 

 nating Moming-Glory. 125. The same further advanced ; its two thin seed-leaves expanded. 



FIG. 126. A grain of Indian Com, seen flatwise, divided through the embryo, which is 

 viewed lying on the albumen, which makes the principal bulk of the seed. 



FIG. 127. Another grain of Corn, cut through the middle in the opposite direction, divid- 

 ing the embryo through its thick cotyledon and its plumule, the latter consisting of two 

 leaves, one enclosing the other. 



FIG. 128. The embryo taken out whole : the thick mass is the cotyledon ; the narrow 

 body partly enclosed by it is the plumule ; the little projection at its base is the very short 

 radicle enclosed in the sheathing base of the first leaf of the plumule. 



FIG. 129. A grain of Indian Com in germination, 



7* 



