46 



growth of the albumen is not so uniform, in these whole groups 

 of families being characterised by its presence or absence. 

 The albumen formed in the embryo-sac is called Endosper- 

 mium, while that formed in the nucleus is called Perisper- 

 mium. When the embryo-sac does not fill the nucleus, and 

 the embryo does not fill the former, both perisperm and en- 

 dosperm are developed, as seen in Nymphaeacese and Hydro- 

 peltidese ; also in Piperacese. In Chelidonium majus, the en- 

 dosperm is alone developed : and this is the case with all 

 Papaveracese, Ranunculacese, Umbelliferse, Rubiacese, and 

 principally the case in all the orders of Lindley's group Albu- 

 minosai. The perisperm is probably developed in all families 

 which have what is called albumen centrale. 



2. On the Structural Relations and Extent of the Albu- 

 men. — In most cases the albumen lias the form of the seed on 

 a reduced scale. A remarkable deviation is seen in Convol- 

 vulus. The endosperm consists of a double spindle-shaped 

 body, with two wing-like appendages, between which the 

 cotyledons are placed. In many of the Scrophulariacea^, the 

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

 seed, remain as appendages to the albumen. Albumen, as 

 well as all other parts of plants, consists essentially of cellular 

 tissue, the cells of which have contents. Cytoblasts are seen 

 only seldom in the cells of albumen, but may be seen very 

 well in Zea Mays. The cells present all the varieties of ordi- 

 nary parenchyma, but never any spiral structure. The walls 

 of the cells are generally thin, simple, without evident con- 

 figuration, as in the case of the albumen farinaceum and car- 

 nosum. The walls are often thick and grown together, so 

 that the cells look as if they were cut out of a homogeneous 

 mass, as in the albumen oleosum and corneum. In the 

 Rubiacese there are thin spots in the horny albumen, as 

 though pores were forming ; the same is seen in the horny 

 albumen of some Palms. In the thin-walled cells pores are 

 very evident. With regard to the general arrangement of 

 the cellular tissue, it has a ray-like texture, from its being 

 developed from the walls of the sac towards the embryo, or if 

 that is very small towards the centre of the albumen. With 

 regard to the contents of the cells of albumen, they do 

 not differ much from those of parenchyma in general. In 

 Alpinia cardamomum, formless masses are observed in the 

 cells of the perisperm. Between the cells of Bothos rubri- 



