The copulation of two coalescing cells, which in these cases often precedes the reproduction, cannot be regarded as a sexual act unless the two copulating plastidsdiffer in size or structure.
These daughter-plastids grow, and multiply in turn in the same way.
But the majority of the chromacea form firm, threadlike cell communities or chains of plastids (catenal coenobia.
Defn: One of the plastids composing the idorgan of Haeckel; -- also called homoörgan.
Defn: A permanent colony of cells or plastids which may remain isolated, like Rotifer, or may multiply by gemmation to form higher aggregates, termed zoides.
The community of the plastidsremains in most cases very loose, and each single plastid retains in a great measure its own individual independence.
For the answer to this fundamental genealogical question we must return to the theory of plastids and the hypothesis of spontaneous generation which we have already discussed (vol.
Very many Protista remain for life simple plastids or individuals of the first order.
The degree of development, however, is dependent upon the greater or less division of labour among organs, and on the differentiation of the plastids and organs.
Others, indeed, form colonies or republics of plastids by the union of several individuals.
The simple cytods (Gymnocytoda), naked particles of plasma without kernel, like the still living Monera, are the only plastids which directly come into existence by spontaneous generation.
Concerning the relation of these four forms of plastidsto spontaneous generation, the following is the most probable:--1.
Each of these two main groups of plastids is again divided into two subordinate groups, according as they possess or do not possess an external covering (skin, shell, or membrane).
A phytomoneron, the globularplastids of which secrete a gelatinous structureless membrane.
A phytomoneron, the round plastids of which (bluish-green in colour) secrete a shapeless gelatinous mass; in this the unnucleated cytodes increase continually by simple cleavage.
Contractile vacuole simple (in fresh-water forms) or absent; plastids yellow or brown always present; reserves fat.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "plastids" in a variety of sentences. We hope that you will now be able to make sentences using this word.
