  We report the results of our search for disturbed (interacting) objects among
very isolated galaxies. The inspections of 1050 northern isolated galaxies from
KIG and 500 nearby, very isolated galaxies situated in the Local Supercluster
yielded five and four strongly disturbed galaxies, respectively. We suggest
that the existence of "dark" galaxies explains the observed signs of
interaction. This assumption leads to a cosmic abundance of dark galaxies (with
the typical masses for luminous galaxies) that is less than ~1/20 the
population of visible galaxies.
