SECT. I. ORGANOGRAPHY AND GLOSSOLOGY. 31 



ively the names of Exogenoe and Endogence. The 

 former names are derived from peculiarities connected 

 with the structure of the seed ; the latter, from a con- 

 sideration of the internal organisation of the plants 

 themselves. 



(34.) Dicotyledones, or Exogence. 

 (1.) Structure of the Seed. 



Beans, peas, almonds, the kernels of our stone fruits, 

 &c. afford us familiar examples of the structure of the 

 seeds of dicotyledonous plants (fig. 22.). When the 



outer skin is removed, we find that they are composed 

 of two large fleshy lobes (a), termed "cotyledons," 

 which are attached to a small rudimentary germ (6), 

 almost entirely concealed between them. The entire 

 mass forms the " embryo," and the skin which invested 

 it is termed the " seed-cover." After the seed has 

 been sown, and germination has commenced, the two 

 cotyledons expand and represent (what in fact they 

 are) a pair of imperfect leaves, but differ in many 

 respects from the leaves which are subsequently de- 

 veloped. One extremity of the little germ to which 

 the cotyledons are attached, is termed the " radicle," 

 and this descending into the ground becomes the root. 

 The other extremity is termed the "plumule," and 

 consists of the rudimentary leaves and stem. In these 

 examples, where the embryo occupies the whole space 

 within the seed-cover, the fleshy cotyledons contain the 



