What is "plastids"

Morphon \Mor"phon\, n. [Gr. ?, p. pr. of ? to form.] (Biol.) A morphological individual, characterized by definiteness of form, in distinction from bion, a physiological individual. See Tectology. --Haeckel. Note: Of morphons there are six orders or categories:

1. Plastids or elementary organisms.

2. Organs, homoplastic or heteroplastic.

3. Antimeres (opposite or symmetrical or homotypic parts).

4. Metameres (successive or homodynamous parts).

5. Person[ae] (shoots or buds of plants, individuals in the narrowest sense among the higher animals).

6. Corms (stocks or colonies). For orders 2, 3, and 4 the term idorgan has been recently substituted. See Idorgan.

n. (plural of plastid English)