92 SCIENCE PRIMERS. [xxn. 



ascends, rarely developing sheathing leaves, and the 

 radicle elongates and branches. 



135. The albumen consists of a mass of cells con- 

 taining starch, albuminoids (Pars. 17, 20), &c., provided 

 for the nourishment of such embryos as possess it. 

 It is usually formed within the embryo-sac (Par. 116). 

 There is no organic connection whatever between the 

 embryo and the albumen with which it is in contact, 

 but yet the growing tissues of the former withdraw 

 nourishing matter from the most distant part of the 

 latter. 



136. Seeds, like fruits (Par. 129), are provided with 

 various means for aiding their dispersion, in the 

 shape of accessory growths, colour, juicy coverings, 

 &c. Many have the testa produced into a thin wing 

 (pine-seeds), or are covered with long hairs (cotton), 

 or have a tuft of hairs at one end (willow-herb), or at 

 the base (willow) ; others become mucilaginous when 

 moist, and thus adhere to the ground on alighting at 

 a fit spot for growth (cress) ; or are supposed to attract 

 birds by their brilliant colours, as certain tropical 

 plants of the pea tribe, the pods of which open so as 

 to expose the seeds ; others have a juicy testa (pome- 

 granate, magnolia, pseony) ; and still others, a fleshy 

 cup or covering (an aril) formed by a growth from 

 the funicle (Par. 130) (passion-flower and spindle- 

 tree). The nutmeg-tree has a i -seeded fruit like 

 a peach, that splits open and exposes the nutmeg, 

 surrounded by an aril of a brilliant scarlet colour : 

 this aril no doubt attracts pigeons, which swallow 

 the nutmegs, and transport them from island to island 

 of the Moluccas. 



137. The vitality of seeds is very variable as to 



