an extended position the second needle 130 can be utilized for the withdrawal of a parenteral agent form an ampoule and on completion of the filing of the chamber of the syringe the second needle can be moved to a position at which the needle 119 is exposed within the body and the first hook shaped needle is brought into engagement with the chamber to allow for the injection of the parenteral medium into the body of a patient the fourth embodiment of fig1 and 13 comprises a cannula which is substantially similar to that of the first embodiment described in relation to fig1 to 5 except that the chamber includes a reservoir 140 which is remote from the body of the device and which is in communication with a recess 141 provided in the body 142 of the device through a tube 143 the hook portion 145 of the needle 146 can be brought into selective engagement with the recess 141 it is envisaged that the fourth embodiment would have application in the collection of fluids such as blood from the body of a patient whereby the blood collection bag incorporates the cannula of the embodiment as a unitary component and there is no need for assembly prior to its utilization the fifth embodiment shown at.