In a tubular pressure chamber a drop of a DNA solution with gold particles suspended therein is atomized at the opening of a cannula by a pressure impact. The fog droplets containing the gold particles and the DNA entrained by them, are pressured by the pressure impact through a restriction at the end of the pressure chamber and thereby accelerated and focused. They subsequently traverse in free flight an evacuated specimen chamber and impact in a narrowly limited target area with a predetermined pulse, cells fixed on a holder, thereby penetrating them.