from the drug reservoir 76 is accomplished much like in the first preferred embodiment of the present invention i e by displacement of the drug reservoir itself again access to the reservoir 76 may be had by way of a needle 82 inserted through a septum 84 disposed within access port 86 and the drug exits the reservoir 76 via exitway 88 the second configuration of the second preferred embodiment is shown in fig5 a motor 90 drives a worm gear 92 that meshes with a toothed bar or rack 94 the rack 94 is fixedly attached or otherwise operatively coupled on one end to the bottom of the drug reservoir 96 the drug reservoir 96 is shown as having flexible i e collapsible sides 98 rather than bellows like sides as in the other figures the exact shape of the sides is not necessarily critical of primary importance is that the sides allow the reservoir 96 to be displaced so that drug introduced by needle 100 through septum 102 disposed in port 104 may be delivered via exitway 106 to a specific desired location in the patient 39 s body the third preferred embodiment of the present invention is shown in fig6 the drug infusion assembly comprises a reservoir 108 including a base 110 and bellows 112 the bellows 112 preferably is annealed in a bellows like.