Page:An introduction to physiological and systematical botany (1st edition).djvu/324

 294 do not ascend, the functions of a real Cotyledon, as far as air is concerned, and those of the Albumen may be united in these lobes, as is the case with most Leguminous plants; which is rendered more probable, as several of the latter have the corresponding parts likewise remaining under ground. Hence the divided Vitellus of the Cyamus is to be considered as a pair of subterraneous Cotyledons, and the plant consequently ranges near its natural allies the Poppy tribe, as Mr. Salisbury, without the aid of physiology, has shown in the Annals of Botany, v. 2, p. 70, 75.

Testa, the Skin, contains all the parts of a seed above described, giving them their due shape; for the skin is perfectly formed, while they are but a homogeneous liquid. This coat differs in thickness and texture in different plants. It is sometimes single, but more frequently lined with a finer and very delicate film, called by Gærtner Membrana, as may be seen in a Walnut, and the kernel of a Peach, Almond, or Plum. Jn the Jasmine a quantity of pulp is lodged