fig1 and 2 illustrate an implanter embodying the invention which comprises a housing for two parts 10 and 12 which are bolted together . the housing is generally t - shaped with the central stem of the t comprising a handle generally designated 14 the lower end of which is enlarged to form a step for housing a pivot joint for the lower end of a pistol grip lever 16 . for convenience the pivot for the pistol grip lever 16 is provided around one of the securing screws 18 which serves to bolt the two parts 10 and 12 together . the left hand section of the t includes a chamber generally designated 20 within which can be fitted a tube 22 containing pellets 24 of a drug which is to be used to promote fattening of cattle or the like . at the forward end of the device there is situated a hollow needle 26 into which and through which the pellets are urged by a mechanism which will be described in more detail with reference to fig2 . by forcing the sharpened open end 28 of the needle under the skin of an animal ( typically behind the ear lobe of the animal ) the pellets can be inserted or implanted below the level of the skin from where the drug will be dispersed to promote the fattening of the animal . the right hand section of the t denoted by reference numeral 30 comprises a housing within which is located the mechanism for pushing the pellets 24 out of the tube 22 and through the needle 26 . it will be seen from a study of the outside features of the implanter shown in fig1 that the device is readily adapted to be used single - handed by an operator and leaves his other hand free so that he can either steady the implanter or the animal or both . in fig2 the cross section reveals the plunger pin 31 which is driven forward as the pistol grip lever 16 is squeezed in a rearward direction so as to pass first of all through an aligned aperture in a retaining clamp 32 ( to be described in more detail hereinafter ) and then through the hollow interior of a tube 22 located within the chamber 20 and finally through the aligned entrance passage 34 to enter the hollow interior 36 of the hollow needle 26 . forward movement of the pin 31 will thus result in displacement of a drug pellet form such as 24 in the tube 22 into and through the hollow needle 26 for implanting as previously described . a return spring 38 is stretched as the pin 31 is moved in a forward direction and when the pistol grip lever 16 is released , the pin 31 is withdrawn to its rest position as the spring 38 relaxes . the pin 31 extends from a shuttle 40 which runs in the interior of the housing extension 30 . to this end the spring 38 is attached to an upstanding spigot 42 forming part of the shuttle 40 . movement of the pistol grip lever 16 is imparted to the shuttle 40 through an inextensible flexible cord 44 which is anchored at one end in a tapering aperture 46 in the shuttle and at its other end in a tapering hole 48 in the housing just in advance of the upper end of the pistol grip lever 16 . the cord 44 is formed with enlarged bulbous ends which cannot pass through the small ends of the respective tapering apertures 46 and 48 so that once in position , the cord remains under tension under the action of the spring 38 . it will be seen however that for replacement and during initial assembly , insertion of a cord involves simply the forward movement of the shuttle 40 so as to allow the rear end of the cord to be released from the aperture 46 and having done that the slack cord can then be pulled rearwardly by a small amount from the aperture 48 and can then be slid sideways out of that aperture . the cord 44 passes around a first pulley 50 carried at the upper end of the lever 16 and subsequently around a second pulley 52 mounted about a pivot 54 in the housing . after passing around the pulley 52 , the cord extends directly to the shuttle 40 . rearward movement of the lever 16 will produce rearward movement of the pulley 50 and due to the velocity ratio of the arrangement , a movement of l along the arc of movement of the axis of the pulley 50 will produce a corresponding movement of approximately 2l of the shuttle 40 in the forward direction . thus if a total stroke of 5 &# 34 ; or thereabouts is required for the pin 31 , a total movement of approximately 21 / 2 &# 34 ; only is required between the forward position of the lever 16 ( as shown in fig2 ) and its fully retracted position ( not shown ). it is this feature primarily which allows the device to be used with one hand since the 21 / 2 &# 34 ; movement of the lever 16 relative to the handle section 14 can be readily accommodated by the span of a man &# 39 ; s hand . although the link 44 has been described as a cord it is to be understood that this may be replaced by a chain or by a belt or a wire or any other convenient flexible device . the chamber 20 is adapted to receive tubes such as 22 of differing length by means of the spring - loaded clamp 32 . this comprises an l - shaped member which is denoted by reference numeral 32 which is adapted to slide in a forward and backward direction in a passage 56 formed in the housing and which houses a spring 58 which is compressed when the l - shaped member 32 is slid backwards . to facilitate the rearward sliding of the member a button 60 protrudes through a slot 62 formed in the housing . in operation , the button 60 is pushed as far back as possible and a tube 22 is inserted into the chamber 20 . the button 60 is then released so that the l - shaped clamp member 32 springs forward under the action of a spring 58 so as to clamp the tube 22 in the chamber . after the pellets 24 have been implanted from one tube , the spent tube can be removed from the housing by forcing back the button 60 against the spring 58 and shaking the implanter so that the spent tube falls out of the chamber which is then ready to receive the next full tube . it will be appreciated that after each implantation , the implanter must be re - loaded with a fresh tube and this disadvantage of the embodiment shown in fig1 and 2 can be obviated by using either of the two remaining embodiments which will now be described . fig3 and 4 illustrate an alternative implanter the internal mechanism of which is identical to the implanter shown in fig1 and 2 but which is modified so as to accommodate between the handle 14 and pistol grip lever 16 a rectangular section passage 64 which replaces the chamber 20 of the previous embodiment . at its front end the cross section of the passage 64 is enlarged at 66 and a magazine generally designated 68 and which includes ten tubes for retaining drug pellets and which is adapted to be used with the implanter shown in fig3 and 4 , is shown in three views contained in fig5 and 7 . a magazine constructed on these lines is shown in more detail to an enlarged scale in fig8 and a cross section through the magazine is shown in fig9 . the magazine is retained by means of a rectangular plate formation 70 which is located and formed integrally with the front of the tube assembly forming the magazine and the dimensions of this plate are such that it is just accommodated within the enlarged section 66 and the dimensions of the remainder of the magazine are such as to be accommodated within the remainder of the rectangular passage 64 . the two sides of the magazine 68 include a series of parallel indentations 72 , 74 etc . which are best seen in fig8 . these indentations are engaged by two complementary parallel abutments 76 and 78 formed approximately midway down one side wall of the passage 64 ( see fig3 ) and on the other side by two spring clips 80 and 82 which are formed with indentations 84 and 86 at their upper ends as shown in fig4 . the indentations 84 and 86 are aligned with the upper abutment 76 and the spring clips 80 and 82 extend into the passage 64 so that when a magazine 68 is pushed down into the passage 64 , the two clips 80 and 82 are urged outwardly and the magazine is resiliently held in position and located by means of the engaging abutments 76 and 78 and the bent parts of the clips 80 and 82 formed by the indentations 84 and 86 . the two abutments 76 and 78 are located along the length of the passage 64 so that when the lowermost indentation 88 of the magazine is impaled on the one side by the abutment 76 and on the other side by the indentations 84 and 86 , the lowermost tube 90 ( see fig5 and 8 ) is aligned with the hollow needle 26 and ( although not shown in fig3 ) the pin 31 . in view of the location of the magazine 68 by the interaction between the flange 70 and the enlarged cross section 66 , no additional locating means is required to accommodate cartridges of differing length . the only requisite is that the cartridge shall be long enough for part of the length to be engaged by at least part of the abutments 76 and 78 as the magazine is pushed through the passage 64 . fig8 and 9 demonstrate more clearly the detailed design of the magazine 68 . each of the cylindrical bores 92 , 94 etc . ( shown in fig9 ) is normally filled with a number of drug pellets 24 although for clarity only the lowermost bore 96 is shown as filled with pellets in the cross - section view of fig9 . in order to facilitate filling of the magazine 68 , each of the bores 92 , 94 , 96 etc . is formed with a reduced diameter opening at its right - hand end , the diameter of the opening being smaller than the diameter of the pellets 24 so as to prevent the pellets from passing therethrough and the other end ( the left - hand end in fig8 and 9 ) of the bores is of sufficient diameter to allow the pellets to be introduced therethrough . the right - hand end of the bores 92 , 94 , 96 etc . are then closed by means of a strip of foil or like material 98 typically adhesive - backed foil having formed therein a plurality of holes 100 , 102 etc . which align with the circular bores 92 , 94 , 96 etc . but are of smaller diameter than the diameter of the pellets 24 so that with the foil in position , the pellets are trapped within the bores . small radial cuts such as 104 are formed around the holes 100 , 102 etc . to facilitate the bursting open of the holes to allow the passage therethrough of the pellets under the action of the pin 31 as the latter is moved in a forward direction . if it is desired that the pellets are sealed into the magazine against the ingress of moisture etc . a further layer of foil may be applied to opposite ends of the magazine so as to cover the openings at opposite ends of the bores 92 , 94 , 96 etc . before the magazine is used , the foil overlying the foil layer 98 is removed and the magazine slipped into the passage 64 . an alternative embodiment of implanter is shown in fig1 to 14 . fig1 is a perspective view of this alternative implanter which with regard to the operating mechanism is identical to that shown in fig1 and 2 but , as in the case of the embodiment shown in fig3 and 4 , the forward end of the housing is modified and the chamber 20 is replaced by a chamber adapted to receive a cylindrical magazine generally designated 106 in fig1 . as shown in fig1 the implanter is formed from a two - part housing 10 &# 39 ; and 12 &# 39 ; and referring to fig1 and 14 , the housing section 12 &# 39 ; is formed with a part cylindrical shell portion 108 in advance of the pistol grip lever 16 . a complementary aperture is formed in the other housing part 10 &# 39 ; which can be closed by a cover generally designated 110 also of part cylindrical form . when the cover 110 is in place ( as shown in fig1 ) a generally cylindrical chamber is formed within the housing into which a cylindrical magazine 106 can be fitted . the cover 110 is cut away to form a window 112 through which the cylindrical magazine can be seen and which gives access to the external surface of the magazine to allow the latter to be indexed to permit different regions of the magazine to be aligned with the hollow needle 26 . a spring catch 114 retains the cover 110 in position and an index spring 116 ( as shown in fig1 ) engages the undulations of the external surface of the magazine 106 . the undulations in the external surface of the magazine 106 lie between radial protrusions containing axial bores within which are located pellets . fig1 which is cross section through the front end of the implanter shown in fig1 illustrates the cylindrical magazine and shows one of the bores 118 filled with pellets 120 which is aligned with the axis of the pin 31 and the interior 36 of the hollow needle 26 . it will be seen from fig1 that by appropriate positioning of the radially directed indentation in the index spring 116 , so one of the bores in the cylindrical magazine 106 will always be aligned with the pin 31 and hollow needle 26 . a refinement shown in fig1 comprises a window 122 through which the upper bore in the cylindrical magazine can be seen . by providing an appropriate window in the wall of each bore or by forming the cylindrical magazine 106 at least in part from transparent or semi - transparent material , so it will be possible to see whether or not there is a charge of drug pellets ready to be implanted or whether the bore aligned with the needle is an empty one . a further advantage of the index spring 116 is that it will readily permit the cylindrical magazine to be indexed in one direction ( i . e . clockwise as shown in fig1 ) but will not so readily allow indexing in the opposite anti - clockwise direction as shown in fig1 . in this way , by indexing the cylindrical magazine by one step in the same circular direction after each of the charges of drug pellets contained in each bore will be used in turn until the whole of the cylinder is spent . as shown best in fig1 and 14 , the cylindrical magazine 106 includes a hollow central core 124 which is joined to the interior of the cylindrical array of tubes by means of radial limbs 126 forming a so - called spider . the core 124 extends axially beyond the ends of the cylindrical array of tubes to form stub shafts 128 and 130 as shown in fig1 . the housing section 12 &# 39 ; is cut away to form semi - circular recesses into which the stub shafts 128 and 130 fit and the cover 110 is formed with a lip 132 at one end and a lip 134 at the other end ( see fig1 ) which overlies the protruding semi - circular section of the stub shafts 128 and 130 and inhibits lateral movement of the cylindrical magazine 106 . it will be appreciated that provided the core section 124 remains the same , the axial length of the cylindrical array of tubes 106 is variable subject to a maximum dimension which will fit within the chamber . thus shorter length cylindrical magazines ( not shown ) may be used accommodating smaller doses of pellets where required . although not shown in fig3 to 14 , actuator means may be provided for indexing the magazine 68 or the cylindrical magazine 106 and the means may be independent of the pistol grip lever 16 or may be operated by each full squeeze of the lever 16 so that the magazine is indexed by one tube section for each operation of the implanter . in this event , means is also provided for indicating when all of the pellet - containing tubes have been emptied in a given magazine . typically this may be in the form of a brightly coloured mark along the edge of the magazine ( particularly the cylindrical magazine 106 ) which will become visible in the window 122 when the last batch of pellets from that magazine has been implanted .
an implanter by which pelleted drugs can be inserted or implanted under the skin of an animal typically to promote fattening of beef cattle and the like . the device includes a thurst pin which can be pushed through a tube containing the pellets to eject them into and through a hollow needle at the front of the device . a mechanism acts on the pin to push it in the forward direction and a return spring acts to return it to its rest position . the mechanism includes a trigger lever as part of a handle assembly and movement is transmitted to the pin through a flexible link such as a cord or wire or belt or chain . the latter passes around abutments so as to reverse the direction of movement so that the pin is effectively pulled in the forward direction , the link being attached to a shuttle to which the rear of the pin is attached . a velocity ratio of for example 1 : 2 is employed so that the pin travels twice the distance that the trigger lever travels thus enabling the device to be held and operated in one hand . the tubes may be inserted one at a time in one embodiment . in other embodiments the tube - receiving region of the device is adapted to accept an array of tubes joined together to form a magazine typically in the form of a flat pack in which they are side by side or in the form of a cylinder .