PART I. ORGANOGRAPHY, 



of the relatively smaller embryo of Nux vomica, Fig. 351 ; in. 

 the seed of Hyoscyamus, already mentioned, it is curved within 

 the albumen ; in the seed of Lychnis dioica, Fig. 352, it is 

 curved, but lies on the outside of it, and almost completely sur- 

 rounds it, while in the Indian Corn, Fig. 353, it is placed to one 

 side of it. 



An embryo that is well developed, like that of the Bean, 

 Figs. 354 and 355, possesses four parts, a stemlet, or caulicle ; 

 at the lower end of this the beginning of the root, called the 

 radicle ; near the upper end of the caulicle two thickened bodies 

 more or less resembling leaves and homologous with them, the 

 cotyledons ; and between these a small bud-^ 

 called the plumule. Thus, in the embryo, 

 all the organs of vegetation are already 

 present except plant hairs. 



The cotyledons, although in their 



.. c 



Fig. 353. 



Frc. 354. 



IV- <f 



355- 



FlG. 353. — Seed of Indian Corn, showing embryo placed to one side of the albumen. 

 (After Sachs). 



F'iG. 354. — Embryo of Bean. 



Fig. 355. — The same, with one of the cotyledons turned back to show the plumule, a, 

 the caulicle; b, the radicle; c, the plumule; d and d' , the cotyledons. 



nature leaves, and sometimes doing for a time the work of foli- 

 age, as those of the Maple and Morning-glory, are commonly 

 thickened and surcharged with nourishment which serves to feed 

 the growing plantlet ; in many instances this function is the 

 only one they discharge. This is the case with the embryos ol 

 the Pea and Oak. In these instances they do not rise above the 

 soil at all in germination, but remain buried in the ground until 

 their supply of nutriment has been exhausted by the growing 



