56 EMBRYO. 



tyledons in some cases (as in Capsella, according to 

 Meyen), being evolved before the radicle ; whilst in 

 others, as in Draba, they seem to be evolved at the 

 same time. With the development of the cotyledons at 

 the upper end of the axis of the Embryo, the axis is 

 extended further in the form of what is termed radicle 

 towards the micropyle, whilst at its upper extremity at 

 the base of the two cotyledons, is developed the first 

 bud or plumula, which is more or less evident in differ- 

 ent seeds before germination. 



306. Suppose the proper development of these parts 

 to have ensued, and the seed in which they are con- 

 tained placed in moist earth, etc., the 



Fig. 50. extended axis of the Embryo below the 

 cotyledons elongates a little immediately 

 beneath them, so that the cotyledons are 

 removed as it were from the other end 

 of the radicular axis, which is now be- 

 yond or out of them : either nearly the 

 whole of the radicular axis, as in the 

 common Bean, dives below the ground 

 to form the root, or else the end of it 

 only, as in some Cruciferae, the upper part 

 of it rising to form the stem : the cotyledons are then 

 either elevated above the ground, and unfold as leafy ex- 

 pansions, or else remain below, and after serving their 

 purpose wither away ; and the plumula elongates and de- 

 velopes itself upwards towards the light, as the first 

 bud, and adding to, or forming the young stem. 



307. From what is stated, it must be remembered 

 that originally the cotyledons are formed out of the axis 

 of the embryo, and not the radicular and plumular axis 

 from them ; and that the extended axis of the embryo 

 below the cotyledons, or radicle as it is called, may in 

 some cases produce both root and stem, whilst in others 

 nearly the whole becomes root ; but that as far as re- 

 gards minute structure, it is doubtful whether a differ- 

 ence exists in the embryo state between those parts of 

 the radicular extension of the axis serving these two 



