Abstract:
A number of racks make up a stack. An upper rack includes releasable catches received into orifices in the next lower rack to releasably attach the two racks to one another. A loader and receptacle cooperate with one another to release the bottommost rack from the stack and deposit it into the receptacle where pipette cones held therein are accessible for use. The bottom rack is placed into the loader where it is held by catches engaging ribs of the rack. The stack of racks with the loader attached is placed onto the receptacle. The stack of racks is pressed downwardly. The downward movement releases the bottom rack from the loader. At the same time, studs projecting up from the bottom of the receptacle engage catches of the second-from-the-bottom rack and free the bottom rack. The bottom rack now rests freely in the receptacle.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to assemblies comprising stacks refills containing elements such as pipette cones. 
     2. Background of the Invention 
     An assembly of this type is known comprising a series of stacked trays each carrying pipette cones, the trays being enclosed in a case of transparent material in the form of a tower that is closed at its top end. The tower can receive a loader at its bottom end, thereby temporarily fixing the trays of the stack to one another. Since the trays are placed one on another in the stack, it is necessary to turn the tower upside-down to place the loader at its top end in order to prevent the trays and the cones becoming dispersed. It is only afterwards that the tower can be put back the right way up. The loader is in turn mounted on a rack or carrier. With the stack and the loader received in this way on the rack, the assembly is arranged in such a manner that downward pressure on the stack causes it to move downwards and a tray to be loaded onto the rack. Thereafter the rack is removed from the loader and the stack to give access to the pipette cones of the tray thus received on the rack. That type of tower has the advantages of being relatively simple to operate, that it saves space for storing the trays and thus the cones, and that it avoids direct contact between the user and the trays or the cones, which could contaminate them. Nevertheless, the assembly is still relatively bulky and difficult to manipulate. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a refill assembly that is simpler to manipulate and that is more compact. 
     To achieve this object, the invention provides an assembly for elements, in particular pipette cones, the assembly comprising at least two refills suitable for forming a stack and carrying elements, loader means for receiving the stack and separating one of the refills from the remainder of the stack, and fixing means for fixing the refills to one another within the stack, wherein at least one of the refills comprises the fixing means. 
     Thus, since the refills are fixed directly to one another, there is no need to provide a rigid case containing the stack of refills. Under such circumstances, in the absence of such a case, the height of the stack decreases as the refills are used up. This gives rise to a considerable saving of space. The assembly nevertheless remains simple to manipulate. 
     Advantageously, the fixing means comprise fixing portions suitable for mutual male-female engagement. 
     Thus, the fixing means are compact. 
     Advantageously, the loader means are suitable for applying force to the fixing portions so as to disengage them. 
     Advantageously, on each refill, the fixing means comprise an orifice, and a catch suitable for engaging the orifice of another refill. 
     Advantageously, the loader means include a member suitable for applying force to the catch from a side of the orifice opposite from the catch. 
     Advantageously, the loader means are suitable for carrying the stack prior to unlocking the fixing means. 
     Thus, the stack is supported by the loader means before the user causes a refill to be released from the stack. 
     Advantageously, the loader means are suitable for carrying the remainder of the stack after the fixing means have been unlocked. 
     Thus, the remainder of the stack is supported separately from the released refill. 
     Advantageously, the loader means are suitable for carrying the stack or the remainder of the stack via a single refill. 
     Advantageously, the assembly includes fixing means for fixing the stack to the loader means, in particular prior to the refill fixing means being unlocked. 
     Thus, it is easy to move the assembly without running the risk of causing it to fall apart. 
     Advantageously, the stack fixing means are suitable for fixing a single refill of the stack to the loader means. 
     Advantageously, the assembly includes fixing means for fixing the remainder of the stack to the loader means, in particular after the refill fixing means have been unlocked. 
     Thus, it is easy to access the released refill without causing the remainder of the stack to come apart. 
     Advantageously, the fixing means of the remainder of the stack are suitable for fixing a single refill of the remainder of the stack to the loader means. 
     Advantageously, the assembly includes centering means for centering the stack on the loader means. 
     This makes them easier to assemble. 
     Advantageously, the loader means comprise at least one portion in relief that is movable between a locking position in which it prevents relative displacement of one of the refills and a transfer position in which it allows such displacement. 
     Advantageously, the assembly includes return means for returning the portion in relief into the locking position. 
     Advantageously, the portion in relief is suitable for being moved from the locking position to the transfer position under the effect of the portion in relief being subjected to a force from the refill. 
     Thus, the refill is released under the effect of the user applying a force in this direction to the assembly, thereby reducing the risk of the refill being released in untimely manner. 
     Advantageously, the loader means are suitable for unlocking the refill fixing means when the refill is in an in-use position for the elements. 
     Thus, unlocking to separate a refill is automatic. Having the refills fixed directly in one another therefore does not prevent the assembly being simple to manipulate. 
     Advantageously, the loader means are suitable for unlocking the refill fixing means under the effect of the stack moving relative to the loader means. 
     Advantageously, the loader means comprise a receptacle suitable for receiving one of the refills in an in-use position for the elements after the refill has been separated from the stack. 
     Advantageously, the assembly includes centering means for centering one of the refills on the receptacle. 
     This facilitates transfer of a refill onto the receptacle. 
     Advantageously, the loader means comprise a loader suitable for receiving the stack, and a receptacle suitable for receiving one of the refills in the in-use position for the elements from the loader. 
     Advantageously, the assembly includes means for centering the loader on the receptacle. 
     Advantageously, the receptacle is suitable for receiving the refill from the loader under the effect of the stack moving relative to the loader mounted on the receptacle. 
     Advantageously, the assembly is arranged in such a manner that the stack provides greater resistance to said movement when the loader is separate from the receptacle than when it is mounted on the receptacle. 
     This reduces the risk of a refill being released in untimely manner from the stack while the loader is not received on the receptacle. 
     Advantageously, the receptacle is suitable for unlocking the fixing means. 
     Advantageously, for the portion in relief belonging to the loader, the receptacle is suitable for placing the portion in relief in an intermediate position between the locking position and the transfer position, or in the transfer position, when the loader is received on the receptacle. 
     Thus, the position of the loader on the receptacle makes it easier to release the refill. This reduces the risk of release occurring outside the receptacle without making it more difficult to release a refill on the receptacle. 
     Advantageously, the assembly is arranged in such a manner that when the loader is not received on the receptacle, one of the refills co-operates by a camming effect with the loader so as to tend to hold the portion in relief in the locking position when a force is applied to the stack in order to achieve said displacement. 
     Advantageously, the portion in relief is secured to a tab extending in an opening in a wall of the loader means, in particular of the loader. 
     Advantageously, the portion in relief is secured to a flexible wall of the loader means, in particular of the loader. 
     Advantageously, each refill comprises a tray and at least one rib parallel to the tray and projecting from a side face of the refill. 
     This rib can co-operate with the portion in relief for fixing and/or releasing the refill. 
     Advantageously, each refill comprises a tray and spacers suitable for supporting the tray on a plane support and at a distance therefrom. 
     Thus, the refill when separated from the stack can be used directly as a rack without needing to be associated with a rack specifically provided for that purpose, e.g. in the receptacle, as is the case in prior devices. This eliminates the problem which consisted in ensuring proper centering between the refill to be released and the receiving rack in order to obtain accurate coincidence of their respective orifices arranged in a matrix, where failure to obtain such centering would either prevent release from taking place or else cause the cones to be dispersed. Furthermore, since the receptacle no longer has to carry a rack to begin with, it can be used successively to receive refills carrying elements of different sizes. Finally, the racks can be designed so that they themselves constitute a stack which is closed at least in part, thereby causing the elements carried by at least some of the racks to be isolated from the outside. These elements are thus protected from the surroundings. 
     Advantageously, one of the orifice and the catch is contiguous with an edge of the tray. 
     Advantageously, the assembly is arranged in such a manner that receiving a refill in the in-use position on the receptacle causes the refill to be fixed rigidly to the receptacle. 
     Advantageously, each refill includes at least one catch suitable for co-operating with a portion in relief of the receptacle in order to achieve said rigid fixing. 
     Advantageously, the assembly includes a stand suitable for directly supporting the stack when the loader is carrying the stack and when the receptacle is not receiving the loader. 
     Advantageously, the receptacle includes a lid and a holder suitable for extending in register with elements of a rack received in the receptacle so as to prevent the elements from leaving the rack when the lid closes the receptacle, the holder and the lid having means for releasably securing the holder to the lid. 
     The invention also provides an assembly for elements, in particular for pipette cones, the assembly comprising at least one refill suitable for carrying elements and forming a stack with an identical refill, loader means for receiving the stack and for separating the refill from the remainder of the stack, and fixing means for fixing the refill to an identical refill in the stack, wherein the refill comprises the fixing means. 
     Other characteristics and advantages of the invention will appear further in the following description of two preferred embodiments given as non-limiting examples. In the accompanying drawings: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cutaway perspective view of a first preferred embodiment of the assembly of the invention prior to loading a rack in the case; 
     FIGS. 2 and 3 are two views on a larger scale showing two details of FIG. 1; 
     FIGS. 4 and 5 are respectively a longitudinal section and a cross-section of the FIG. 1 loader; 
     FIG. 6 is a view half in longitudinal section and half in elevation showing the assembly of FIG. 1; 
     FIG. 7 is a view on a larger scale showing a detail of FIG. 6 with the deformed parts; 
     FIGS. 8 and 9 are views analogous to FIGS. 6 and 7 showing the FIG. 1 assembly after a rack has been loaded into the box; 
     FIG. 10 is a view half in side view and half in cross-section showing the assembly of FIG. 1; 
     FIG. 11 is a view analogous to FIG. 10 showing the assembly after a rack has been loaded; 
     FIG. 12 is a view on a larger scale showing a detail of FIGS. 10 and 11; 
     FIGS. 13 and 14 are perspective views of the FIG. 1 box respectively with a rack and without a rack; 
     FIG. 15 is a view half in elevation and half in cross-section of the box of FIG. 13; 
     FIG. 16 is a view half in cross-section and half side view of the box of FIG. 13; 
     FIG. 17 is a perspective view from below of a rack in a second embodiment; 
     FIG. 18 is a perspective view from above of the box in the second embodiment for co-operating with the rack of FIG. 17; 
     FIGS. 19 to  21  are fragmentary longitudinal section views respectively of the box of FIG. 18, of the rack of FIG. 17, and of the box receiving the rack; 
     FIGS. 22 to  24  are partially cutaway views respectively in perspective, in elevation, and in perspective showing the box of FIG. 18 of the second embodiment in its closed position and receiving a rack with a holder; 
     FIG. 25 is a perspective view of the FIG. 24 assembly with the box open; 
     FIG. 26 is a perspective view of the lid of the FIG. 22 box on its own; 
     FIG. 27 is a perspective view of the holder of FIG. 22 on its own; 
     FIG. 28 is a perspective view of a stand forming a portion of the second embodiment of the invention; 
     FIG. 29 is an overall view of the second embodiment received on the stand of FIG. 28; and 
     FIG. 30 is a view analogous to FIG. 29 that has been partially cut away. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the first embodiment of the invention, the assembly of FIG. 1 is designed to carry elements, and specifically pipette tips or cones  3 . The assembly comprises a plurality of refills  2 , in this case identical to one another, and specifically in the form of racks or carriers. It also comprises a receptacle, in this case in the form of a box  4 , and a loader  6 . The box and the loader constitute loader means. 
     The racks  2  are described first. Each rack comprises a generally plane tray  8  in the form of a plane rectangle. In conventional manner, the tray  8  presents orifices  14  disposed regularly in a matrix of rows and columns, adapted to receive the pipette cones  3  and to support them. More precisely, the tray  8  has a top face  10  and a bottom face  12  which are respectively slightly convex and slightly concave. This makes it easier to take the pipette cones  3  with a multichannel pipette by making it easier to engage the cones in a row successively on the respective channels of the pipette by an appropriate rocking motion of the user&#39;s hand. 
     The rack  2  has two longitudinal walls  16  and two transverse walls  18  extending perpendicularly to the general plane of the tray  8 , from the same face thereof, extending from its edges and giving the rack the general shape of a rectangular parallelepiped. At the junction between the tray and each longitudinal or transverse wall, the rack has a shaped shoulder  20  suitable for receiving the bottom free edges of the longitudinal and transverse walls of another rack  2  when two racks  2  are stacked directly one on another in corresponding positions, as shown in FIG. 1, with their trays  8  being parallel. Thus, the tray  8  of a lower rack in a stack penetrates a little way between the walls  16 ,  18  of the rack above it. As a result, the two racks are centered and spaced apart relative to each other. In addition, the longitudinal walls  16  and transverse walls  18  of the two racks then extend continuously one from another, thereby isolating the cones  3  to some extent from the surroundings. The racks are thus suitable for being stacked on one another to make up a stack in the form of a tower which can have a height of ten to twelve racks before the cones start being used. To clarify the drawings, the stack shown in the figures has only four racks. The walls of each rack constitute spacers for supporting the rack on a plane support with the tray  8  of the rack extending at a distance therefrom. 
     The racks  2  have direct fixing means that emerge between one another in the stack, said fixing means being constituted by fixing portions suitable for providing male-female coupling for fixing the racks together. Specifically, with reference in particular to FIGS. 2,  3 , and  13 , each rack has two rectangular orifices  22  formed in the tray  8  in the middles of its transverse edges, contiguous with the shoulder  20 . In addition, each transverse wall  18  has in its middle, at its bottom free edge, a catch  24  extending towards the inside of the rack and suitable for engaging in the orifice  22  of the rack beneath it in the stack. 
     This catch has a plane bottom guide face  26  that slopes relative to the wall  18  carrying the catch and relative to the tray  8 , facing towards the bottom rack of the stack. The orifice  22  has a top edge designed to come into contact with the guide face  26  and presenting a top guide facet  24  that slopes relative to the tray  8  and to the adjacent end face  18  so as to be parallel to the guide face  26  of the catch. When two racks  2  are stacked one on the other, the guide faces  26  of the two catches  24  come into surface contact with the facets  28  of the corresponding orifices  22 , thereby forcing outwards each transverse wall  18  that carries a catch  24  so that the catch  24  can move past the edge of the orifice  22 . Because of the resilience of the material constituting the wall  18 , the catch  24  is then returned towards the orifice  22  so as to be received therein. 
     The edge of the orifice  22  contiguous with the bottom face  12  of the tray is sharp and male. The top end of the catch  24  has a top shaped female shoulder suitable for receiving the sharp edge. The sharp edge and the shoulder are arranged in such a manner that when the catch  24  is engaged in the orifice  22 , the racks can be separated only by forcing the catch  24  outwards. 
     Each rack has a rectilinear rib  30  parallel to the tray  8  and projecting from the outside face of each longitudinal wall  16 , contiguously with the shoulder  20 , and also has a rectilinear rib  32  parallel to the tray and extending from the outside face of each transverse wall  18  contiguously with the free bottom edge of said wall. The ribs  30  and  32  are suitable for co-operating with the loader and the box as explained below. Each rack  2  can be made as a single piece of plastics material. 
     The box  4  is described below. It has a plane bottom wall  36 , two longitudinal walls  38 , and two transverse walls  40  extending perpendicularly from the bottom wall to give the box the general shape of a rectangular parallelepiped. At their free top edges, the longitudinal walls  38  have respective setbacks  42  making it easier to take hold of a rack  2  housed in the box in order to extract it. The box  4  has a lid  44  generally in the form of a rectangular parallelepiped connected to the rear longitudinal wall  38  via hinges. With the lid in the closed position, the box isolates the rack contained inside the box from the outside. 
     The box has studs  46 ,  47  extending parallel to one another parallel to the walls  38 ,  40 , projecting from the bottom  36  of the box to a level close to the level of the free top edges of the walls. Six of the studs  46  are close to the center of the box (they are referred to as “central” studs) and the other six studs  47  extend close to the transverse walls  40  (they are referred as “peripheral” studs), two studs close to the vertical edges of each wall and a middle stud in the vicinity of the center of the wall  40 . The purpose of the central studs  46  is specifically to support the tray  8  of the rack via its bottom face  12  bearing on the studs when the rack is received in the box. The peripheral studs  47  come into contact with the inside faces of the transverse walls  18  and the longitudinal walls  16  of the rack to center it relative to the box. The two middle peripheral studs penetrate slightly into the respective orifices  22 , in particular to finish off centering. 
     The loader  6  is described below, in particular with reference to FIGS. 4 and 5. It has two longitudinal walls  50  and two transverse walls  52  that are generally parallel in pairs, giving it the general shape of a rectangular parallelepiped and defining two mouths. At their bottom free edges, the longitudinal walls  50  have respective setbacks  54 . The loader presents a general midplane that is perpendicular to its walls  50  and  52  and to its height direction, subdividing the loader into two portions, a top portion and a bottom portion, such that the length and the width of the top portion are smaller than the length and the width of the bottom portion. This difference in size is obtained by each of the walls  50  and  52  having a profile that is S-shaped. On the outside faces of the walls, the transition between the top and bottom portions is marked by a sloping facet  56 , whereas on their inside faces the transition is provided by a shoulder forming a plane facet  58  perpendicular to the walls and facing downwards. The length and the width of the inside volume of the bottom portion are large enough to enable it to be engaged on and around the box  4 , unlike the dimensions of the top portion. When the loader  6  is mounted in this way on an open box  4 , the inside faces of the walls  50  and  52  of the bottom portion face the outside faces of the walls  38  and  40  of the box. The loader then bears against the free top edges of the walls of the box via its facet  58 , or alternatively it bears against studs projecting therefrom. 
     The inside faces of the bottom portion have ribs  60  extending parallel to the height of the loader for the purpose of bearing against the outside faces of the walls  38  and  40  of the box so as to contribute to centering the loader on the box. The ribs  60  are chamfered at their bottom ends so as to facilitate engaging the loader on the box. 
     The means providing co-operation between the loader  6  and the rack  2  are described below. Each longitudinal wall  50  of the loader has catches  70 , in this case two such catches, projecting from the inside face of the wall. Each catch  70  has its tip extending downwards. It is designed to enable a rack  2  to move downwards relative to the loader while preventing it subsequently from moving upwards. Each catch  70  has a plane top face  72  facing upwards, sloping downwards away from its top edge on the inside face and inwards towards the inside of the loader. The catch then continues downwards with a plane lower face  74  extending perpendicularly to the longitudinal inside face. Each catch  70  is contiguous to the top edge of the wall  50  and is located halfway between the longitudinal middle of said edge and a respective one of its ends. 
     When a stack of racks  2  is inserted into the top mouth of the loader, the longitudinal ribs  30  of the rack situated at the bottom end of the stack bear against the sloping top faces  72  of the catches  70 . The four catches  70  are suitable for supporting the stack in this position which is referred to as the “topmost” or “unfixed high” position, the rack or the stack of racks still being capable at this stage of being extracted upwards from the loader. Each of the longitudinal walls  52  of the top portion of the loader has two vertical ribs  76  projecting from the inside face of said wall. The ribs  76  contribute to spacing and centering the bottom rack of the stack in the loader, by bearing against the longitudinal ribs  32  of the rack. These ribs  76  have chamfered top ends so as to facilitate insertion of the rack  2  or the stack into the loader. 
     Each of the longitudinal walls  50  in the top portion of the loader has a rectilinear rib  78  of triangular profile extending horizontally and projecting from its inside face beneath the catches  70 , in register with the gap between them, but not in register with them. This rib  78  has sloping top and bottom faces respectively facing upwards and downwards. 
     Each of the transverse walls  52  in the bottom portion of the loader has two openings or holes  80  of rectangular shape into which there extend respective tabs  82  of corresponding shape. Each tab  82  is connected to the associated wall  52  via its top edge only, thereby allowing the tab  82  to move resiliently in bending through the opening  80 , both inwards and outwards relative to the loader  52 . When at rest, each tab  82  lies in the thickness of the wall. The outside face of the tab has an S-shape identical to that of the wall. 
     Each tab  82  has a catch  84  extending towards the inside of the loader projecting from the inside face of the transverse wall  52  when the tab is in its rest position. The catch  84  has two upper ribs  86  spaced apart from each other and facing each other at the same height, each having a top chamfer. The two ribs  86  could be replaced by a chamfer and a vertical face (which amounts to filling the empty space between the two ribs  86  with material). The catch  84  also has a horizontally shaped tip  88  extending inwards, projecting from the ribs  86  and sloping slightly upwards when the tab is in its rest position. 
     Starting from the above-mentioned topmost position, a small force urging the stack of racks downwards causes the racks  2  to move down to a “high” or a “fixed high” position. During this downwards movement, the longitudinal ribs  30  of the bottom rack of the stack force the catches  70  on the longitudinal wall of the loader outwards by forcing the longitudinal walls  50  that carry them to deform elastically outwards so as to allow the ribs to go past. Once they have gone past, the longitudinal ribs  30  of the rack bear against the two longitudinal ribs  78  of the loader and co-operate in centering therewith, and the transverse ribs  32  of the rack bear against the tips  88  of the catches  84 . The longitudinal ribs  78  of the rack and the tips  88  of the catches prevent further downwards movement of the stack in the absence of force being applied by the user. In addition, the longitudinal catches  70  of the loader prevent the longitudinal ribs  30  of the rack from allowing the rack to move back upwards relative to the loader. The stack of racks  2  is thus fixed to the loader  6  solely via the rack that is situated at the bottom end of the stack. The subassembly can thus be manipulated in any direction quite freely without running the risk of the racks coming apart. The assembly of the invention advantageously has a rack cover  90  that is identical to the racks  2  in all features except that its tray  8  does not have any orifices  14  for receiving cones and does not have any fixing orifices  22 . When fixed via its catches  24  to the top rack in the stack, it serves to protect the cones of that rack and to hold these cones in their orifices  14 . When the above-mentioned subassembly is provided with this cover  90 , it can be turned in any direction without running the risk of losing any cones. This position of the loader and of the stack is shown in FIGS. 1,  2 ,  3 ,  6 ,  7 ,  10 , and  12 . In this fixed high position, the subassembly with the loader can be removed from the box  4  or can be replaced thereon. 
     It is assumed below that the subassembly with the loader is received in the high position on the box that does not have a rack, as shown in FIG.  1 . The tabs  82  of the loader have chamfers  91  at their bottom ends that face downwards and that are defined either by a face of the tab or by ribs thereon as shown, said chamfers projecting from the inside face of the transverse wall  52  when the tab is in its rest position. These chamfers  91  can be seen more particularly in FIGS. 4,  5 ,  7 , and  9 . When the loader  6  is engaged on the box  4 , the chamfers  91  come into contact with the free top edges of the transverse walls  40  of the box and thus act as cams for forcing the respective tabs  82  outwards. This outwards movement causes the tip  88  of the catch  84  of each tab to move away from the rack, which rack continues to be supported by the internal longitudinal ribs  78  of the loader. Thus, the bottom rack is no longer supported by the catches  84 . In addition, the position of the catch then allows the stack to move downwards on application of a force that is much less than that which would be needed in the absence of the box. In this respect, it is specified that FIG. 2 shows the parts assembled together but not deformed even though the tab in this position is normally deformed so that the catch  88  leaves a clear path for the rack. In addition, in this position, the central and peripheral studs  46  and  47  of the box already extend very slightly between the walls of the bottom rack. In particular, the middle peripheral studs  47  have their top ends bearing against the sloping bottom faces  26  of the transverse catches  24  of the rack so as to cause them to start moving apart, i.e. outwards as shown in FIG.  2 . The ribs  60  serve to center the loader  6  (and thus the outline of the rack) relative to the box  4 . 
     When the user forces the stack of racks downwards, e.g. by pressing on the top of the stack, the longitudinal ribs  30  of the bottom rack force the longitudinal ribs  78  of the loader to move apart together with the walls  50  carrying them, thereby enabling the rack to move downwards until it is received in the box. During this movement, the middle peripheral studs  47  move the catches  24  of the bottom rack further outwards by the camming effect of the ramps at the ends of the studs engaging the faces  26  of the catches. Immediately before the bottom rack is received so that it bears against the central studs  46  of the box, the top ends of the middle peripheral studs  47  come to bear via the inside of the bottom rack through the corresponding orifices  22  with the catches  24  associated with the next rack up in the stack. The stud  47  bears against the bottom face  26  of the catch, thereby urging it outwards by a camming effect. This outwards movement is sufficient to disengage the catch  24  of the next rack up from the orifice  22  of the rack that is about to be received in the box. This unlocks the rack fixing means. 
     As the stack moves downwards, the next rack up takes up the fixed high position. Once the downwards movement has come to an end, the central studs  46  prevent any further downwards movement of the stack. The subassembly comprising the remainder of the stack and the loader  6  fixed thereto can then be removed from the box  4 . This operation gives access to the rack  2  received in the box and above all to its cones  3  which can then be used directly. 
     After the cones have been used, it suffices to remove the rack  2  from the box, to replace the subassembly on the box, and to load a new full rack in the box by using the same operations of forcing the stack downwards. The same operations can be repeated until the last rack of the stack which, once in the box, leaves the cover  90  on its own in the loader  6 . 
     As shown in FIG. 2, each rack can, at each location of its bottom edge that is to come into register with the catch  88 , present a bottom sloping ramp face  91  facing towards the inside of the rack and suitable for coming into surface contact with an associated sloping top ramp face  93  of the catch  88  and facing towards the transverse wall  52  of the loader carrying the tab  82 . Thus, when the loader is supporting the stack of racks without being received on the box but standing on a work surface, the two ramp surfaces  91  and  93  come mutually into contact. Thus, under the effect of gravity or of untimely thrust from a user, the stack of racks tends to move downwards with the camming co-operation between the two faces  91  and  93  tending to move the catch  88  towards the inside of the rack, i.e. in the direction opposite to the direction that would allow the rack to be released when the loader is received on the box. This provides a safety feature that locks the stack of racks against moving down inside the loader whenever the loader is not received on a box. 
     The box whose dimensions are not tied to the dimensions of the cones  3  can be associated with stacks of racks  2  containing cones of different diameters. 
     As the racks are used up, the height of the assembly decreases, thereby saving space. 
     A second preferred embodiment of the invention is described below with reference to FIGS. 17 to  30 . The assembly is very similar to that of the first embodiment. Nevertheless, it incorporates a number of variants, which can indeed be implemented independently of one another. 
     In the assembly constituting the first embodiment, the rack  2  in its in-use position in the box  4  is fixed rigidly thereto by friction, in particular by the contact between the middle studs  47  and the transverse catches  24 . The rack is thus clamped to the box. 
     However, it is advantageous for such an assembly to be capable of being put into an autoclave while in this configuration. Typically, the autoclave includes a step of raising temperature to 121° C. over a period of 20 minutes. However, it has been found that under the effect of temperature rise, the plastics material of the rack softens and the rack deforms so that the clamping is reduced to nothing. After a period in the autoclave, the assembly cools down but its parts retain their deformation: there is no longer any clamping. Consequently, the rack is no longer fixed to the box and that gives rise to problems when users take cones or knock the box over. 
     The first of the variants described below seeks to mitigate that drawback. Each rack  2  comprises above each catch  24  another catch  101  that likewise projects inwards. The middle studs  47  for unlocking purposes present respective cavities  100  in their peripheral faces within which the corresponding catch  101  is received once the rack  2  has been received in the box  4  in the in-use position. The catch  101  is received in said cavity because of the resilience of the wall  18  which is elastically deformed immediately prior to the rack being received in the box. The cavity  100  forms an edge with which the catch  101  comes into engagement to prevent the rack  2  from being separated from the box unless a particularly large amount of force is exerted in this direction by the user. They are thus rigidly fixed together. In this position, the catch  101  can be received in the cavity, possibly without exerting force on the middle stud. 
     By means of such fixing, the assembly can be subjected to successive passages through an autoclave without degrading fixing between the rack and the box. Furthermore, in the above-described case where the catch  101  is received without applying force to the rack  2 , the passage through an autoclave does not give rise to any deformation. The assembly of the invention can thus be subjected to repeated passages through an autoclave. 
     Another variant incorporated in this embodiment consists in making at least one plane rib  102  parallel to the studs in the box and interconnecting some of them so as to reinforce them. Specifically, the rib  102  extends in a middle longitudinal plane of the box and interconnects the middle peripheral studs  47 . 
     Furthermore, as seen in the first embodiment, when the loader  6  supports the stack of racks  2  outside the box  4 , the stack of racks stands on the catches  88  and thus on the flexible tabs  82 . Unfortunately, in the event of an impact, it can happen that the stack of racks exerts sufficient force on the tabs as to cause at least one of the tabs to break. 
     A variant incorporated in the second embodiment seeks to mitigate that drawback. To this end, the assembly constituting the second embodiment includes a stand  106  shown in FIGS. 28 to  30 . The stand is made as a single part. It presents a central body  108  of shape and dimensions close to those of a rack  2  except that it does not have a tray between the top edges of its walls, but in contrast it does have a bottom  110  between their bottom edges. 
     The rectangular top edge  112  of this central body is suitable for directly supporting the bottom edge of the rack  2  at the bottom of the stack. For this purpose it has cutouts, in particular for providing a volume for receiving the catches  24  of the rack. The stand  106  also has a rectangular peripheral collar  112  surrounding the central body  108  at a distance therefrom, and of slightly smaller height. The central body  108  converges slightly in an upward direction while the collar  112  flares slightly in that direction. The stand  106  is designed to be suitable for receiving the loader  6  supporting a stack of racks after it has been removed from the box  4 , as shown in FIGS. 29 and 30. For this purpose, the loader  6  is placed on the stand  106  by inserting its walls between the central body  108  and the collar  112 . On penetrating into the loader, the central body comes into contact with the bottom edge of the bottom rack  2  of the stack that it is supporting. Under such circumstances, the tabs  82  of the loader are no longer carrying the stack of racks. The stack of racks can thus accommodate considerable impacts without running any risk of damaging the loader. The loader  6  together with the stack can then subsequently be taken freely from the stand  106  and put back on the box  4 . 
     To fix the stand  106  to the loader  6  in the position of FIG. 29, the collar  112  has fluting  114  to form ribs of semicircular cross-section on the inside face of the collar. When the loader  6  is placed on the stand  106 , the walls of the loader are jammed between the fluting  114  and the central body  108 . This provides a friction connection between the loader and the stand. Specifically, some of the fluting is located so as to extend in register with the tabs  82 . 
     Furthermore, the assemblies in both embodiments of the invention are designed to be suitable for receiving pipette cones of different models, in particular cones with a variety of collar heights, where the term “collar” is used for the larger portion of the cone that extends above the tray of the rack while the cone is being carried by a rack. 
     In the first embodiment, in order to place high-collar cones in the box, it is necessary to provide sufficient space between the curved surface of the rack (against which the collars bear) and the end wall of the lid. Under such circumstances, when small-collar cones are placed in the box, should the user for any reason happen to overturn the box (e.g. while putting it in an autoclave), then the cones escape from their housings. On opening the box, the user will find cones that are disposed in a jumble and that are thus unusable. 
     In the second embodiment, a variant is incorporated that seeks to remedy that drawback. Thus, with reference to FIGS. 22 to  27  the assembly constituting the second embodiment has a holder  120  comprising a flat rectangular body  121  presenting orifices  122 . Overall, the body has the same shape and the same dimensions as the top tray  8  of the racks  2 . The holder  120  has struts  124  projecting from its transverse edges, e.g. two such struts, suitable for engaging in blind orifices  126  in the transverse walls of the lid  44  so as to secure the holder in releasable manner to the lid. These orifices  126  extend in this case close to an edge of the lid that is a bottom edge when the lid is in the closed position. The struts  124  therefore slope. 
     The holder also has spacers  126  in the form of fingers extending from a plane face of the body  121  towards the end wall of the lid  44  so as to maintain a minimum spacing between the body  121  and the end wall of the lid. 
     When cones of low collar height are stored in the box, the holder  120  is mounted in the lid  44 . When the lid is closed, the body  121  comes into register with the collars in the immediate vicinity thereof and prevents them from escaping from the rack, even if the box is turned upside-down. If cones of greater collar height are to be stored, then it suffices to remove the holder  120  from the lid prior to closing it. 
     The box could be implemented with the holder independently of the characteristics of the tower of racks and independently even of the presence of a tower of racks. 
     Refills could be provided in the form of trays provided with legs having mutual fixing tabs. 
     Each of these elements comprising the loader, the box, and its lid can be made as a single piece, e.g. out of plastics material. 
     The assembly could be designed to carry other elements, e.g. ice cream cones.