
spontane genetische veranderungen am zellstamm l (earle)
the chromosomal constitution of a clone of the cell strain ,,l'' was studied by
repeated chromosomal analyses within 2 years.  there resulted the stability of
the cellular clone with regard to the tested feature for the duration of about
one year.
the maximal number of chromosomes amounted to 60-64.  in later tests a spon-
taneous doubling of the chromosomal number (maximum 120 chromosomes) was
ascertained.  the cause of this phenomenon could not yet be cleared up.  this
new chromosomal pattern remained unchanged in the subsequent examination period
of 6 months.
as was proved by these observations, under the present cultivation-conditions
cell populations can be retained stabile in vitro for a certain period.  the
defined substances, however, still imply unknown factors which may have a
mutagenous effect, so that sudden changes of cell populations may result.  the
respective physiological features are hardly known as yet.
