the analysis system 10 shown in fig1 can be held in the hand of a test subject and be used on the spot for blood sugar measurements . for this purpose , the instrument comprises a portable or hand - held device 12 with a magazine guide 16 which can be closed by means of a lid 14 and which receives a disposable annular magazine 18 . an application opening 22 on which the test subject places a finger is provided on the housing 20 of the device 12 in order to collect a blood sample for glucose determination by means of a skin incision . the ring - shaped annular magazine 18 shown in fig2 has a multiplicity of magazine units 24 distributed in the circumferential direction . each magazine unit 24 has a measurement window 26 and a transport element 28 in the form of a pin protruding from the underside of the magazine . the transport elements 28 arranged in a ring shape permit step - by - step indexing and defined positioning of the individual magazine units 24 in a functional position in front of the application opening 22 . as is shown in fig3 , a piercing element 32 and a test element 34 are located in the magazine chamber 30 of each magazine unit 24 . in the functional position , the piercing element 32 can be pushed out radially by means of a reciprocating piercing drive ( not shown ) so that , when the skin is pierced , a small amount of blood is taken up in a capillary channel and is transferred to the test field 34 . the test field 34 is provided with a test chemical that responds to the analyte ( glucose ) with a change of color and can be optically scanned via the measurement window 26 by means of a photometric measurement unit ( not shown ) transversely with respect to the annular plane . the active magazine unit is positioned as precisely as possible in the functional position in front of the application opening 22 and over the measurement unit . for this purpose , the magazine 18 has , next to the transport elements 28 , a plane surface 36 which is held at a defined measurement distance by a device - side three - point bearing on hard support humps 38 , such that the optical beam path is reproducible . in order to keep the position tolerances low , a spring 40 presses on the upper face of the magazine 18 on the opposite side of each of the three support humps 38 in a trigonal planar arrangement . in order to ensure , particularly upon exchange of a magazine , that used piercing elements are not re - used , a device - side light barrier 42 is provided which passes a beam through a transparent area 44 of the magazine units 24 . a sterile film or sealing film 46 that closes off the magazine chamber 30 from the piercing drive is thus scanned , the state of use being directly detectable from the destruction of the film . fig4 to 7 illustrate the sequence of movement for the onward indexing and defined positioning of the magazine units 24 of the magazine 18 in the device 12 ( not itself shown ). for this purpose , a device - side transport mechanism 48 is coupled to a positioning mechanism 50 ( fixing mechanism ) of the device , in order to satisfy said functions by a manipulation of the transport elements 28 of the magazine 18 . both the transport mechanism 48 and also the fixing mechanism thus engage on the transport elements 28 of the magazine 18 . fig4 shows a magazine position in which a magazine unit 24 is held fixedly in the functional position . for this purpose , the positioning mechanism 50 is provided with retaining means 52 , 54 which are arranged on the device and which are in releasable form - fit connection with two diametrically opposite transport elements 28 ( highlighted in black in the drawing ) of the magazine 18 . one of the retaining means is formed by a laterally open bearing eye 52 which , as a bearing point fixed on the device , engages half way round the transport element 28 of the magazine unit 24 located in the functional position . on account of the short distance to the active measurement window 26 of this magazine unit 24 , a low position tolerance is obtained . self - locking with respect to transverse movements is effected by the steep flanks of the bearing eye . thus , the magazine 18 could only still rotate about the fixed pin or retreat linearly from the bearing eye . in order also to prevent a movement in these remaining degrees of freedom , a prismatic gripper 54 engages as retaining means on the diametrically opposite pin . this gripper 54 is urged by a restoring force in the direction of the arrow 56 , for example by means of a spring . the restoring force should be greater than the frictional forces that are caused by the spring suspension of the magazine 18 on the three support humps 38 . in order to permit coupling to the transport mechanism 48 , the gripper 54 is arranged at one end of a two - armed gripper lever 60 , which is able to pivot about the axis 58 . in this arrangement , the active magazine unit 24 is located geometrically precisely in front of the measurement unit in the functional position . the gripper 54 , as the only movable structure involved in this ( and , for example , requiring a clearance for its movement ), is at a distance , corresponding to the diameter of the ring of pins , much farther away from the position - determining bearing point 52 than the measurement unit which is located in the area of the measurement window 26 and which therefore has a precisely defined optical transmission path . however , the self - locking design of the retaining means 52 , 54 for the pins or transport elements 28 suppresses onward transport of the annular magazine 18 to the next magazine unit 24 . in order to permit this transport , the gripper 54 with its catching prism has to be lifted by the transport mechanism 48 actively against the restoring force 56 from its engagement position to its release position , as is shown step by step in fig5 to 7 . for the movement coupling , the transport mechanism 48 has a control cam 62 as cam gear which sits on the output shaft 64 of a motor and drives an excavator lever 68 via a crank pin 66 , while the circumferential contour of the control cam 62 actuates the gripper lever 60 . the excavator lever 68 is mounted over an oblong hole 70 such that it can move to and fro in a generally elliptical movement on a bearing pin 72 fixed to the device and can rotate about this . in the course of this movement , a blade - shaped slide 74 engages on the transport elements 28 and , in interaction with arc - shaped directing contours 76 , 78 , 80 ( fig5 ) of the magazine guide 16 , effects a transport step to the next magazine unit 24 . in the initial phase ( shown in fig5 ) of the onward indexing , the gripper 54 is first of all moved to its release position by the control cam 62 . simultaneously with this , the slide 74 is guided on an elliptical path into the ring of transport elements 28 such that one of the latter is gripped . as a result of the strongly eccentric engagement of this slide movement relative to the friction of the pressing springs 40 against the three support surfaces of the magazine 18 , a torque arises that allows the whole magazine 18 to pivot ( clockwise in fig5 ) about the transport element located in the bearing eye 52 . this pivoting movement is limited by the arc - shaped directing contour 76 against which the ring of transport elements 28 runs ( fig6 ). as soon as the pivoting movement is stopped , only a linear degree of freedom still remains available , which allows the magazine to retreat from the bearing eye 52 until transport elements 28 once again abut the directing contour 78 , such that in the final phase only a rotation of the whole magazine 18 is still possible ( fig7 ). after this rotation has advanced one magazine division , the slide 74 on its elliptical path disengages from the transport elements 28 , and the gripper 54 drops again onto the next transport element located in its catch area , as a result of which the magazine 18 also moves once again into the bearing eye 52 . the magazine 18 is thus once again clearly positioned in front of the measurement unit , but with a new magazine unit 24 . the above - described mechanism never completely frees the magazine 18 . upon removal of a magazine from the system , the gripper 54 would pivot still further into the magazine guide 16 under the restoring force 56 , as a result of which the insertion of a new magazine would be impeded . in order to avoid this , the gripper lever 60 is lengthened and , at its free end 82 , is coupled to the device lid 14 via an adjustment means ( not shown ). the adjustment means , e . g . a connecting rod , is moved by the opening device lid 14 and actuates the gripper lever 60 , such that the gripper 54 moves to its release position , specifically without engaging the slide 74 . this allows the user to place a new magazine into the device without considering the angular orientation of the magazine 18 . to ensure that the magazine 18 does not remain in an intermediate position and is not secured in this position by the once again inwardly pivoting gripper 54 , a transport cycle should first take place after the closure of the housing lid 14 . it should also be ensured , when fitting an already used magazine , that no used piercing elements 32 are used , so as to rule out a danger of infection . for this purpose , the transport cycles should be carried out until , by means of the light barrier 42 as test unit , an unused magazine unit 24 is detected in the functional position .