from
The Collaborative International Dictionary of English v.0.48
Chromatin \Chro"ma*tin\, n. (Biol.)
The deeply staining substance of the nucleus and chromosomes
of eukaryotic cells, composed of DNA and basic proteins (such
as histones), the DNA of which comprises the predominant
physical basis of inheritance. It was, at the beginning of
the 20th century, supposed to be the same substance as was
then termed {idioplasm} or {germ plasm}. In most eukaryotic
cells, there is also DNA in certain plasmids, such as
mitochondria, or (in plant cells) chloroplasts; but with the
exception of these cytoplasmic genetic factors, the nuclear
DNA of the chromatin is believed to contain all the genetic
information required to code for the development of an adult
organism. In the interphase nucleus the chromosomes are
dispersed, but during cell division or meiosis they are
condensed into the individually recognizable chromosomes. The
set of chromosomes, or a photographic representation of the
full set of chromosomes of a cell (often ordered for
presentation) is called a karyotype.
[Webster 1913 Suppl.]