Discontinuous Feed Tube Field of the Invention The invention relates to motorised fruit and vegetable juicers and more 5 particularly to the feed tube of a motorised fruit and vegetable juicer. Background of the Invention Motorised fruit and vegetable juicers are well known. Fruit and vegetable juicers of this kind generally comprise a collection chamber in which 10 is located a frustoconical filter basket, a lower portion of which forms a grating disc. A feed tube is located above the grating disc so that fruit and vegetables entering the feed tube impinge on and are juiced by the grating disc. In conventional domestic fruit and vegetable juicers, the feed tube is integrally moulded with the transparent polymeric cap. However, overfilling of the feed 15 tube and other forms of accidental or abusive usage can lead to a splitting or cracking of the feed tube. The use of detergents to clean a polymeric juicer lid can lead to degradation of the polymers from which the feed tube is constructed, leading to an increased propensity to crack, split or fracture. For this reason, full length metal feed tubes have been proposed and disclosed by 20 the Applicant. The Applicant's PCT application, PCT/AU2004/ooo828 is accordingly incorporated herein by reference. In an all metal feed tube, the lower part of the feed tube obstructs the view of the grating disk through the lid. The present disclosure relates to alternatives, simplifications and cost saving implementations in which 25 something less than the entirety of the feed tube in constructed from metal. This approach of providing a two part, discontinuous or compound feed tube 1 also provides the opportunity to provide additional vibration damping with respect to the lid and upper feed tube area. Objects and Summary of the Invention 5 It is an object of the invention to provide a motorised fruit and vegetable juicer having a discontinuous feed tube. That portion of the feed tube generally above the lid is fabricated from metal and a portion of the feed tube below the lid is fabricated from a polymer. A seal and gasket arrangement may be interposed between the metal and plastic portions to 10 prevent leakage and dampen vibration. Brief Description of the Drawing Figures In order that the invention be better understood, reference is now made to the following drawing figures in which: 15 Figure 1 is perspective view of a motorised fruit and vegetable juicer; Figure 2 is an exploded side elevation of a lid, feed tube, pusher, filter basket and juicing compartment; Figure 3 is a first embodiment of a join between upper and lower 20 portions of a compound feed tube; Figures 4 is a second embodiment of a join between upper and lower portions of a compound feed tube; and Figure 5 is a third embodiment of a join between upper and lower portions of a compound feed tube. 25 2 Best Mode and Other Embodiments As shown in Figure 1, a motorised fruit and vegetable juicer 10 comprises a base 11, a clear or transparent polymeric lid 12, a pulp collection basket 13, a feed tube 14 and a pusher 15. 5 As suggested by Figure 2, a frustoconical filter basket 20 and grating disc 21 are located below the lower opening 22 of the feed tube 14. The filter basket 20 is located within a juicing collector 23. The juice generated by the grating disc 21 passes through the filter portion 123 of the filter basket 20 and into the juicing collector 23. Juice is dispensed from the juicing collector 23 10 through an integral spout 24. As further suggested by Figure 2, the feed tube 14 comprises an upper, generally cylindrical metallic tube section 25 and a lower polymeric tubular section 26. The lower section or portion of the feed tube 26 may incorporate an integral fin, blade or knife 27. The upper, metallic portion of the feed tube 25 comprises a peripheral upper rim 28. A shallow 15 neck 29 is provided below the rim 28 to rigidise the upper of the metallic section. A further indentation or alignment feature 30 cooperates with a longitudinal groove 31 in the pusher. The pusher also includes a relief area 32 for accommodating the knife 27. In essence, the upper and lower sections form a compound feed tube. In all of the embodiments disclosed in this 20 document, the internal bores of the upper and lower sections are round in cross section and of the same diameter. This prevents there from being a substantial step between the upper and lower sections. So that juice does not leak in the join between the upper and lower sections, a gasket or seal has been developed and is disclosed below. 25 Figure 3 suggests one way of joining the upper metallic section 25 of the feed tube to the lower polymeric portion 26. In the example of Figure 3, 3 the lower portion 26 and the optional knife 27 are moulded with, that is to say integral with, the polymeric lid 12. The upper extent of the lower polymeric portion 26 of the feed tube comprises a circumferential groove 33 that is adapted to receive the lower end of the upper section 25 so that the interior 5 diameter 34 of the upper section is flush with the interior diameter 35 of the lower section. The circumferential interior groove 33 has a lower shoulder 36 against which receives the lowest edge of the upper metallic section 34. An annular polymeric gasket 37 surrounds and seals against a lower extent of the upper section 25. The sealing gasket 37 is received by a cooperating 10 circumferential groove 38 that surrounds the uppermost lid opening formed by the polymeric lower section 26. The circumferential groove 38 may incorporate detents 39 or other mechanical features for positioning the gasket 37 within the groove 38. The gasket 37 is retained by a stabilising ring 40. The ring may be polymeric but is more rigid than the gasket 27. The ring may 15 also be provided in the form of a metal flange that is permanently formed with or welded (e.g. 140 in Figure 4) to the upper metal feed tube part. The ring 40 is approximately as wide as the gasket 37 and includes through openings 41 for locating and receiving threaded or other fasteners 42. The flush mounted fasteners 42 are received by an enlarged boss or flange 43 formed in an 20 underside of the polymeric lid 12. Threaded fasteners 42 may be used to compress the gasket 37 between the stabilising ring 40 and the upper surface of the polymeric lid 12. Figure 3 also illustrates that the upper and metal portion of the discontinuous feed tube may have its own knife 127. The metal knife 127 may 25 be welded 128 to the inside of the metal part of feed tube 125. The metal knife 127 is in alignment with the plastic knife 27. The purpose of the metal knife 4 127 is to pre-cut or pre-score the fruits or vegetables that are in the feed tube, thereby making the job of the plastic knife 27 easier. This is intended to reduce wear, fracture or damage to the plastic knife 27. Because the metal knife 127 and the plastic knife 27 are in alignment, the vertical slot 31 in the 5 pusher need not be modified. Another method of joining the upper and lower sections of the feed tube is depicted in Figure 4. In this example, an inner peripheral rim 45 of the gasket sits above the lower portion and has the same inside diameter. The gasket includes a circumferential groove 46 for receiving the lower rim 47 of 10 the metallic upper section 25. Thus, the upper extent of the polymeric section 26 need not include the groove and shoulder 33, 36 disclosed with reference to Figure 3. In the example shown in Figure 5, the polymeric lower section 26 is fabricated separately from the polymeric lid 12. In the example of Figure 5, 15 the upper flange or rim 50 of the polymeric section 26 is thick enough, or includes a plurality of enlargements or bosses 51, so as to receive an array of vertical fasteners 42 that are used to both secure the stabilising ring 40 and compress and locate the gasket 37 with respect to the upper surface of the lid 12. 20 While the present invention has been disclosed with reference to particular details of construction, these should be understood as having been provided by way of example and not as limitations to the scope or spirit of the invention. 5