280 



PERISPERLM OR ALBUMEN OF THE SEED. 



traced ; appearing first as a simple cell (figs. 486, 488), forming others 

 in its interior (figs. 489, 490) ; and finally, the parts of the embryo 

 becoming visible, as in fig. 491, where g r is the axis representing the 

 stem and roots, and c c are the lateral projections, which are developed 

 as leaf-like bodies, called cotyledons {norv^nluv, the name of a plant, 

 having leaves like seed-lobes). 



587. Perisperm or Albumen. As the embryo increases in size, it 

 gradually causes absorption of the cellular tissue in the embryo-sac, and 

 it is sometimes developed to such a degree as to reduce the nucleus and 

 embryo-sac to a thin integument. In such a case the seed consists of 

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

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

 nary 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 encroach- 

 ing slightly on the cells of the nucleus. The cells surrounding the em- 

 bryo then become filled with a deposit of solid matter called albumen, 

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

 this matter some have applied the term perisperm (<KI% \, around, and 

 avi^f*,*, seed) ; others, that of endosperm (IvSo*, within). The name 

 perispermic albumen, or perisperm, is often restricted to that found in 

 the cells of the nucleus alone (fig. 480 ) ; endospermic albumen, or 

 endosperm, to that found within the embryo-sac alone (fig. 480 s e), as 

 in Chelidonium majus, Kanunculaceae, Umbelliferse, &c. Sometimes 

 both kinds of albumen occur in the same seed, as in Nymphaeacea? 



and Piperaceae. Schleiden states, that in some instances the albumen 

 is produced in the region of the chalaza. He also remarks, that endo- 

 spermic albumen is common in Endogens. In some Scrophularias, the 



Fig. 49?. AnatTOpal mature seed of HeUeboms niger cut vertically. The embryo, e, is small 

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

 /, Funiculus. h, Hilum. c, Chalaza. 



Fig. 493. Mature seed of Diphylleia peltata, showing an embryo, e, which occupies a larger 

 portion of the seed than in fig. 494. Letters indicate the same parts as in the previous figure. 



Fig. 494. Ripe seed of Berberis vulgaris, exhibiting a larger embryo, ?, as compared with the 

 perisperm, p. Letters as in figs. 492 and 493. 



