Page:An introduction to physiological and systematical botany (1st edition).djvu/325

 Rh between the Membrana and the Testa, constituting a pulpy seed, semen baccatum, which is distinct from the Acinus, or grain of a compound berry in the Raspberry, the seed of the latter having its proper double covering within the pulp. The Testa bursts irregularly, and only from the swelling of its contents in germination.

Hilum, the Scar, is the point by which the seed is attached to its seed-vessel or receptacle, and through which alone life and nourishment are conveyed for the perfecting its internal parts. Consequently all those parts must be intimately connected with the inner surface of this scar, and they are all found to meet there, and to divide or divaricate from that point, more or less immediately. In describing the form or various external portions of any seed, the Hilum is always to be considered as the base. When the seed is quite ripe, the communication through this channel is interrupted: it separates from the parent plant without injury, a Scar being formed on each. Yet the Hilum is