Page:An introduction to physiological and systematical botany (1st edition).djvu/326

 296 so far capable of resuming its former nature, that the juices of the earth are imbibed through it previous to germination.

There are various accessory parts, or appendages, to seeds, which come under the following denominations.

Pellicula, the Pellicle, called by Gærtner Epidermis, closely adheres to the outside of some seeds, so as to conceal the proper colour and surface of their skin, and is either membranous, and often downy, as in Convolvulus, or mucilaginous, not perceptible till the seed is moistened, as in Salvia verbenaca, ''Engl. Bot. t.'' 154. Perhaps the covering of the seed in Chenopodium, called by Gærtner Utriculus, is merely a Pellicula.

Arillus, the Tunic, is either a complete or partial covering of a seed, fixed to its base only, and more or less loosely or closely enveloping its other parts. Of this nature is the pulpy orange-coloured coat in Euonymus, t. 362, the beautiful scarlet cup in Afzelia, and the double membranous coat in Hippophäe, t. 425, which last invests the seed within the pulp of the berry.