A double syringe for supplying a fluid to a microfluidic system, having - a cylindrical outer chamber that defines a reservoir for receiving the fluid to be supplied, - a cylindrical inner chamber that is arranged within the outer chamber and that, in its distal cylinder base surface, comprises an outlet opening for connecting with the microfluidic system, and that is in fluid communication with the outer chamber via through holes, - an inner piston that is axially movable in the inner chamber and that, in a closed position, closes the through holes on the inner chamber side, and in a release position, releases the through holes and enables a fluid flow from the outer chamber to the inner chamber, and - an annular piston that is axially movable in the outer chamber toward the distal end of the outer chamber, i) that, in a proximal reservoir position, closes off the reservoir for the suppliable fluid, ii) through whose movement toward the distal end a fluid provided in the reservoir is pushed via the through holes into the inner chamber when the inner piston is in its release position, and iii) that, in a distal closed position, closes the through holes from the outer chamber side and, in this way, enables fluid to be drawn back from the microfluidic system into the inner chamber through an axial movement of the inner piston toward the proximal end. - a cylindrical outer chamber that defines a reservoir for receiving the fluid to be supplied, - a cylindrical inner chamber that is arranged within the outer chamber and that, in its distal cylinder base surface, comprises an outlet opening for connecting with the microfluidic system, and that is in fluid communication with the outer chamber via through holes, - an inner piston that is axially movable in the inner chamber and that, in a closed position, closes the through holes on the inner chamber side, and in a release position, releases the through holes and enables a fluid flow from the outer chamber to the inner chamber, and - an annular piston that is axially movable in the outer chamber toward the distal end of the outer chamber, i) that, in a proximal reservoir position, closes off the reservoir for the suppliable fluid, ii) through whose movement toward the distal end a fluid provided in the reservoir is pushed via the through holes into the inner chamber when the inner piston is in its release position, and iii) that, in a distal closed position, closes the through holes from the outer chamber side and, in this way, enables fluid to be drawn back from the microfluidic system into the inner chamber through an axial movement of the inner piston toward the proximal end. i) that, in a proximal reservoir position, closes off the reservoir for the suppliable fluid, ii) through whose movement toward the distal end a fluid provided in the reservoir is pushed via the through holes into the inner chamber when the inner piston is in its release position, and iii) that, in a distal closed position, closes the through holes from the outer chamber side and, in this way, enables fluid to be drawn back from the microfluidic system into the inner chamber through an axial movement of the inner piston toward the proximal end.