from the interruption in the shorter side, a filler tube extended by a centering funnel widening in the direction away from the bottom of the rectangular pocket; the two films of thermoplastics material have holes outside the line of the weld for sprockets which feed the strip along the making up machine, and in particular into the station in which the pockets are filled; the two films are also welded together around these holes, locally increasing the stiffness of the strip and reducing the tendency of the strip to deform in this area during filling. As the sachets are still in a strip when filled, it is important to facilitate deformation of the pocket during this operation and, to this end, a long incision that subsequently delimits eachsachet is made in the strip, transversely to the strip and between the successive pockets. The pockets are sequentially filled with semen, in conjunction with stepwise movement of the strip into the filler station, by means of a tubular needle connected to a tank of semen and introduced into the pockets in succession while the sachets are stationary in the filler station; to this end the needle is moved in longitudinal translation to insert its free end into the filler tube, remains stationary during filling, and is then moved in longitudinal translation in the opposite direction to withdraw it from the tube; in the next station the machine for making up the doses welds the two films of thermoplastics material together to join together the opposite walls of