Ch. VIII, 2] MORPHOLOGY OF SEEDS 



375 



of the nucellus by the endosperm) all of the space within the 

 seed coats. Such are the albuminous seeds, in the germi- 

 nation of which the embryo absorbs the 

 endosperm through its cotyledons. In 

 the ex-albuminous seeds, however, this 

 absorption of the endosperm occurs 

 before germination, and this is the mean- 

 ing of the difference between the two 

 kinds. It is in correlation with this 

 further stage of development that ex- 

 albuminous seeds have so often a Fig. 269. — Grain of 

 plumule, while albuminous kinds have Co ™> in longitudinal 



ii ii i /• i • /• section ; X 3. 



only the undeveloped foundation of a At the right is the 



U..J embryo, showing plu- 



mule, primary root, 



Third of the parts are the seed coats, and hypocotyl. In the 

 Oftenest there is but one, which is thick, J. a * ter can , be seen + the 



7 } nbro-vascular system 



hard, and WOOdy, and has the obvious extending into the large 



function of protecting the embryo against scutellum which 



r ° i forms a haustonal or- 



injury during the period of dissemina- g an for absorbing the 

 tion. Sometimes there is also an inner endosperm,-** (looser 



texture) and eg (more 

 COat, then usually compact texture). It 



membranaceous, and is doubtful whether the 



7 cotyledonisrepresented 



less Often an addi- by the scutellum, by 



tional outer coat, the sheath leaf of the 



plumule, or by both to- 



Called an ARIL, which gether. (From Sachs.) 



is generally loose 

 from the others and has obvious con- 

 nection with dissemination, as in cases 

 earlier mentioned, i.e. the Yew berries 

 (page 351) and the Water-lily seeds 



nous seed, of Castor ( age 3(U ) There fc gome structural 

 Bean, in section ; X 2. r ° , 



The embryo lies em- connection, not yet fully understood, 

 bedded in endosperm ; between these arils and the little insig- 



below is a caruncle. t 



nificant and seemingly functionless swell- 

 ing called the strophiole, occurring near the hilum in 

 some seeds, and the much larger caruncle (Fig. 270), an 



Fia. 270. — Albumi- 



