THE SEED. 91 
26 ar). This arillus, which is known in commerce under the 
name of mace, represents the only structure of this character 
which is properly treated of here. A relatively still more devel- 
oped arillus, but consisting only of a thin membrane, incloses 
the seed of the cardamom. The small, red, cup-shaped body 
of Taxus fruits is also to be regarded as an arillus. 
The arillus always originates at the base of the seed, and is to 
be considered as an outgrowth of the funiculus. 
The pappus, a form of appendage of fruits (page 69), is 
formed by a subsequent outgrowth of the calyx. 
The germination of the seed proceeds in this way, that with a 
Fie. 26.—Fruit of Myristica fragrans, longitudinal section. ar, arillus; s, seed 
(Hager). 
simultaneous evacuation of the endosperm which may be pres- 
ent, the plumule and radicle break through the testa of the 
seed, the former developing to form the stem, and the latter to 
form the root. Thereby the cotyledons, which are sometimes 
fleshy and thick (as in the Bean), sometimes thin and leaf-like 
(Ricinus), are either elevated above the ground and become 
green (Epigea), or remain in the ground until their evacuation 
and rejection (Hypogea, compare page 69). Occasionally, the 
cotyledon still incloses for some time the young leaf-bud 
(Maize). 
