1. A rodent racing device for movement on a trackway of a marked racing area, including: a circular cage housing the rodent, wheels supporting the cage for movement on said trackway, a motor for rotating said wheels at a selected speed and means for increasing Said selected speed of wheel rotation when the rodent runs in said cage to rotate the same.

3. A rodent racing device which includes a marked racing area provided with a trackway upon which the racing device moves, including: a circular cage having side members between which extend spaced rungs, an axle central of said cage and extending between the side members thereof, a substantially semi-circular perch for the rodent within the cage and eccentrically carried by the axle, wheels supporting the cage and a motor for rotating the wheels at a selected speed, movement of the rodent from the perch to the rungs of the cage to rotate the cage increasing the speed of wheel rotation beyond the initial selected speed.

4. A rodent racing device which includes a circular cage within which the rodent may run to rotate the cage, supporting wheels for the cage and a motor for rotating the supporting wheels at a preselected speed, and means for rotating the wheels of said wheel support independently of said motor when the rodent causes rotation of the cage.

5. A rodent racing device, including: a circular cage having a pair of side members and spaced rungs upon which a rodent may run extending between said side members, a pair of wheels on opposite sides of said side members and supporting said cage, a central axle extending between the side members of the cage and said wheels, a perch within said cage and an electric motor including a stator and a rotor, the rotor of which is mounted on the axle and the stator of which surrounds the rotor in driving relationship with the sides of the cage, and means for electrically energizing the stator to produce rotation of the rotor and to rotate the wheels.

9. A rodent racing device, including: a wheeled vehicle, a circular cage, an axle for said cage, and means for supporting the cage between the axle and the wheeled vehicle, an electric motor and a battery for driving the wheels of said vehicle, and a pulley carried by the axle and a pulley secured to a wheel of the vehicle, a continuous belt between said pulleys whereby the electric motor drives the vehicle at a determined speed and a rodent within the cage rotates the cage when it runs therein, to increase the speed of the vehicle movement.

10. A rodent racing device, including: a wheeled vehicle, an electric motor for driving the vehicle at a selected speed, a circular cage within which the rodent is placed, an axle for said cage and support means for the cage secured to said wheeled vehicle, a ratchet freely carried on said axle, a pulley secured to said ratchet and a pulley secured to a vehicle wheel, and a continuous belt extending between said pulleys, a pawl secured to the cage for engagement with said ratchet whereby when the rodent runs within the cage the pawl is in driving relationship to the ratchet to rotate the two pulleys through said continuous belt and to increase the speed of movement of said wheeled vehicle over that by the electrically driven motor.

13. A rodent racing device, cOmprising: a wheeled vehicle, a circular cage having a pair of sides, a dielectric axle extending between said sides and means of support between the axle and the wheeled vehicle, a metal tube carried on the axle, metal contact disks for each side of the cage and secured to the metal tube, one contact disk provided with an insulation segment, and an electrical contact arm for engagement with each contact disk, said wheeled vehicle provided with an electric motor in driving engagement with a wheel of said vehicle, and a battery for energizing said motor, there being wire leads from each contact arm in series with the motor and battery when both contact arms engage the metal contact disks to complete an electrical circuit, and a resistor in series circuit with the motor and the battery when one contact arm engages the segmental insulation on one disk, movement of the rodent upon the interior of the cage rotating the cage to short circuit the resistor and direct full electric current to the motor from the battery.