332 



PEEISPEEM OE ALBUMEN OF THE SEED. 



integuments and embryo alone. In Santalum, Osyris, and Loranthus, 

 Griffith says the ovule is sometimes reduced entirely to a sort of 

 embryonary sac. In Avicennia the embryo, at its maturity, is on the 

 outside of the nucleus and body of the ovule. In other cases it enlarges 

 to a certain extent, filling the embryo-sac completely or partially, and • 

 only encroaching slightly on the cells of the nucleus. The cells sur- 

 rounding the embryo then become filled with a solid deposit called 

 albumen, consisting of starchy, oily matter, and nitrogenous compounds. 

 To this some have applied the term perisperm (tiiI, around, and eiri^f/.a, 

 seed); others, that of endosperm {tvbov, within). The name, perispermic 

 ■albumen, or perisperm, is often restricted to that found in the cells of 

 the nucleus alone, outside the embryo-sac (fig. 576 n) ; endospermic 

 albumen, or endosperm, to that found within the embryo-sac alone 

 (fig. 576 se), as in Chelidonium majus, Eanunculacese, Umbelliferse, 

 and in many Endogens, etc. Sometimes both kinds of albumen occur 



Fig. 689. 



Fig. 590. 



in the same seed, as in Nympheeaceae and Piperacese. In some instances 

 the albumen is produced in the region of the chalaza. In some Scrophu- 

 larias the embryo-sac forms little cavities or bags, which in the ripe 

 seed remain as appendages to the albumen. Seeds in which the 

 •embryo occupies the entire seed, are called exaUmminous (ex, without), 

 as Oompositse, Cruciferse, and most Leguminosae, while others having 

 separate albumen are albuminous. The larger the quantity of albumen 

 in a seed the smaller the embryo. In figs. 588 to 590 the relative 

 proportion which the embryo bears to the albumen or perisperm in 

 different seeds is shown ; e being the embryo with its cotyledons and 

 young root, p the perisperm, t the coverings of the seed, / the funiculus 

 or cord, h the hUum, and c the chalaza. In fig. 588 the embryo is 



Fig. 588. Anatropal mature seed of Helleborus niger, cut TerticaUy. The embryo, c, is 

 small, as compared with the perisperm or albumen, p. t, Spermoderm or coverings of the 

 seed. /, Funiculus, h, Hilum. c, Chalaza. Fig. 689. Matm'e seed of Diphylleia peltats, 

 showing an embryo, e, which occupies a larger portion of the seed than in fig. 588. Letters 

 indicate the same parts as in the previous figure. Fig. 590. Ripe seed of Berberis vulgaris, 

 exhibiting a larger embryo, e, as compared with the perisperm, p. Letters as in figs. 588 

 and 589. 



