DTV. n 



SPERMATOPHYTA 



581 



protoplasm divides to form numerous cells. These by further division 

 fill the whole embryo-sac with the tissue of the endosperm. 



In Angiosperms also the endosperm as a rule compresses the 

 remains of the nucellus. Reserve 



materials such as starch, fatty oil, " ES^r- B 



and aleurone grains are accumulated 

 in the cells (Fig. 563) ; in other 

 cases the greatly thickened walls 

 form a store of reserve cellulose 



JL 



FIG. 565. A, Seed of Hyoscyamus niger, showing 

 the dicotyledonous embryo embedded in the 

 endosperm ; B, seed of Elettaria Cardamomum, 

 enveloped by a thin aril ; the white, mealy 

 perispenn next to the seed-coat encloses an 

 oleaginous endosperm (shaded), in which the 

 monocotyledonons embryo lies embedded. 

 (After BERG and SCHMIDT.) 



FIG. 566. Capsella bursa pastoris. A, Longi- 

 tudinal section of a ripe seed; h, hypocotyl; 

 c, cotyledons ; v, vascular bundle of the 

 funicle ( x 26). B, Longitudinal section of 

 the seed -coat after treatment with water ; 

 e, the swollen epidermis ; c, brown, strongly 

 thickened layer ; *, compressed layer of 

 cells; a, the single persisting layer of 

 endosperm cells containing aleurone grains. 

 (x 250. After STBASBURGER.) 



(Fig. 564). In a few cases, as in Piperaceae, Scitamineae, etc., the 

 nucellus persists and also serves as a nutritive tissue; it is then 



nucellus persists and also serves as a 







FIG. 567. A, Seed of Papaver Rhoeas; fe, 

 the hilum. B, Seed of Corydalis ochro- 

 leuca ; m, micropyle ; c, caruncula. 

 C, Seed of Chel idonium majus. D, Seed 

 of Xymphaea alba with its arillus. 

 (After DUCHARTRE.) 



FIG. 568. A. Myristica fragrans, seed from which the 

 arillus (ar) is partly detached. B, Myristica argentea, 

 seed after removal of the arillus ; Ch, chalaza ; r, 

 raphe ; h, hilum. (After WARBURG, f nat. size.) 



termed PERISPERM (Fig. 565 B}. When lamellae of the perisperm 

 or of this and the seed-coat grow into the endosperm, they usually 

 differ from the latter in colour and contents ; the endosperm is then 

 said to be ruminated (Myristica, Areca). 



