Scotland Under-19 striker Gary Oliver joins Queen of the South from Hearts for an undisclosed fee.
Hibernian sign strikers Islam Feruz and Henri Anier on loan from Chelsea and Dundee United respectively.
DUNDEE UNITED raided the English Championship to land Fulham striker Adam Taggart and Reading midfielder Aaron Kuhl on loan until January.
Celtic have signed 21-year-old Croatian centre-back Jozo Simunovic from Dinamo Zagreb, says the Croatian FA.
Hibernian have signed Henri Anier on loan from Dundee United until the end of the season.
Left-back Kevin McHattie leaves Hearts by mutual consent and joins Kilmarnock on a three-year deal.
Scottish referees say the recent and "ongoing trend of personal and unjust criticism" towards top officials is "unacceptable."
Celtic have announced that development coach Stevie Frail has left the club with Academy manager Tommy McIntyre taking on his responsibilities.