left weft needle 2 a has just inserted a weft thread loop 22 a into the shed 6 and has been beaten up at the beating up edge 10 by means of the reed 11 by means of the left thread lifter 18 a the left weft thread 4 a is raised on the fork 16 a of the weft needle 2 a as a result of the raising of the thread lifter 18 a to an extent such that said left weft thread cannot be grasped by the fork 16 a of the weft needle 2 a on the right side of the shed the thread lifter 18 b is lowered and brings the weft thread 4 b into engagement on the fork 16 b of the weft needle 2 b so that the latter can insert the weft thread loop 22 b into the open shed 6 as shown in fig2 the left weft needle 2 a runs empty into the shed the weft thread 4 a being guided in the guide slot 20 a when the weft thread loop 22 b has been inserted completely into the shed as is evident from fig3 the left knitting needle 28 a grasps the auxiliary thread 24 a and draws the latter through the inserted weft thread loop 22 b and further on through the last loop 30 a of the auxiliary thread 24 a on the right side the auxiliary thread 24 b is interlaced with itself that is to say with its last loop 30 b without being drawn through a weft thread loop.